I had Sclerotherapy 4 days ago and have joint stiffness and pain. Could it be the compression hose?

We treat veins on a daily basis. Staying active is encouraged post treatment. I prefer my patients to walk about a mile a day or be on elliptical cross trainer for 15-20 mins. I ask my patients to avoid lifting heavy stuff ( more than 20 pounds ) or doing high impact training (like jumping jacks) just because they can make the legs sore. There is limited evidence that compression socks impact results of spider veins treatment. There is more evidence that compression helps with symptomatic relief and impact the result of varicose and reticular vein treatment and after DVT. I recommend wearing compression for the first 24 hours after treatment and during the daytime for at least 2 weeks. As far as your soreness you can take tylenol, motrin or Aleve. Since NSAIDS work by inhibiting platelet function, they don't impact treatment results of veins.

Vein specialist recommend medical compression stockings 20-30 mmHg for a week after treatment  during the day for optimum results, not necessary while sleeping. 
Avoiding strenuous exercise and heavy lifting is recommended, however, walking is encouraged after treatment. It is also important to cover the area or apply sun protectant to avoid sun exposure of the area that was treated. Again, activities that should be avoided after sclerotherapy treatment are heavy lifting, strenuous exercises, and sun exposure of the treated area; but normal activities and walking are beneficial. 
In case that the pressure you are feeling does not go away or increases or if there is increased pain and swelling, seek medical assistance quickly to prevent any possible complication related to deep vein thrombosis or superficial thrombophlebitis after sclerotherapy. 
All the best,  

I tell my patients that they can exercise the same day as the treatment as long as they wear compression (for example-yoga pants).  I see no reason to not exercise for one week.  I also recommend compression for only 48 hours post treatment.

It is not uncommon to feel achy after sclerotherapy. Generally, this is a side effect of the medication injected into the veins. Your doctor may choose to use a different medication. Most patients feel their symptoms improve after a few days and using Tylenol or Ibuprofen provides enough relief.  I generally recommend light exercise such as walking at least 20 minutes a day after sclerotherapy. Because your doctor knows you best, you can ask your doctor if non-strenuous exercise may help relieve your symptoms. There are many types of compression stockings that may be better suited for you. Although many stockings are less expensive and available online, the medical grade stockings measured and fitted for you tend to provide much better comfort and symptom relief. I find that some patients like the leggings, tights, or hosiery instead of the knee or thigh highs, especially during the non-summer months. If your symptoms are not getting better, talk to your doctor about your concerns. We want to make sure you are satisfied with the treatment process and achieve the best results.

Sclerotherapy can be done for a variety of reasons. If it was done for spider veins (which is usually why a dermatologist will perform the procedure), then refraining from exercise is usually not necessary beyond the immediate post-procedural period. If it was done to treat larger veins though, it's recommended to avoid heavy lifting or intense exercise to keep the pressure in the veins low so they do not reopen. It is unlikely that a dermatologist was performing sclerotherapy for these larger veins, however. In fact, vein doctors like myself encourage light exercise as soon as a day after the procedure. Being active helps reduce the chance of clot formation. I ask my patients to refrain from intense exercise for 1-2 weeks after treatment of the Saphenous vein, but not smaller tributaries.
As for the aching, if you weren't aching before the procedure when wearing hose, it's unlikely that the hose is causing you to be achy now. If you feel the urge to be active, taking brisk walks and stretching wouldn't cause harm. For more intense exercise, contact your treating physician to see if they approve of it. 4 days post-procedure I suspect they will.

I assume that the dermatologist injected small spider veins (that all what they usually do), therefore you do not have ANY restrictions for exercise after the procedure. Compression stockings use after spider sclerotherapy is controversial at best provided that your doctor is sure that you do not have significant venous reflux (I assume that he did a Doppler ultrasound before the procedure). Try not to wear the compression stockings, you will feel better.