5 months later after having Halo around my mouth, I look like hell: Why did this happen?

I agree with everything said. All lasers can cause an acne-like break out. It doesn't matter which one. The discoloration after an acne flare usually lasts a few months but will fade don't worry. The reason you go to a good laser clinic is exactly because these side effects happen. I recommend going back to the clinic you originally visited so they can take a good look and work with you. Best of luck. 

It is not uncommon after any resurfacing procedure to break out for a period of time.  I wonder if you had predisposing factors (like sun exposure or being on any photosensitizing medications) prior to your procedure.  I would strongly recommend returning to your provider to see what happened in your case specifically.  Good luck.

Sorry to hear about the side effects after the Halo laser treatment.  Without pictures, I would presume the laser caused a flare of antibiotics (not uncommon) and some reactive post-inflammatory hyperpigmentation.  
Sometimes acne is activated after laser treatments, sometimes is the post care creams or products that are used that aggravate this.
We  stress the post skin care regimen to patients to prevent acne.  But if acne occurs we start treatment quickly  with antibiotic creams or tablets or even injections.  This will prevent the post-inflammatory hypeigmentation.
Overall, the post care regimen is very important.
Ken Oleszek, MDLa Fontaine AestheticsDenver , CO

It's hard to tell without any photos. It would be best to follow up with your initial laser provider  and get evaluated.