I had bbl arm lipo seven weeks ago and I have constant pain in my right arm and a weird rash. Is it fibrosis? (photo)

Hi and thanks for your question.
Liposuction for arm is really hard both for surgeons and patients because there are too much vascular, lymphatic and neural tissues. During the liposuction some of these tissue can be damaged and because of the usage of the arm healing process continues longer than the other parts of the body. You can feel lumps in your arm, there may be reactive lend node enlargement. You can feel pain or burn sensation after arm liposuction because the neural tissue may be damaged during liposuction. All these problem will decrease with time you can do massage slightly to decrease these symptoms but don’t worry these kind of problems can be observed in most of the patients 

The description you've provided is very unique - it could be fibrosis due to the Liposuction. The rash is something that is not easy to connect to surgery. Perhaps it could be a dermatological problem. I think that this is something that you should discuss with both a Dermatologist and your surgeon. 

You are early after surgery.  At this time you need to massage the lipo areas to help smooth out all these lumps.The rash may be completely unrelated.Pain is not unexpected, should improve with massage.