Is this a chemical burn from the injections? (Photo)

There appears to be some hyperpigmentation after the injections.  Usually you would expect this to be more linear in the shape of the treated vein from hemosiderin that leaks into the surrounding skin after injection but if some of the solution was injected under the skin (which can happen when treating especially small veins) then it may simply be post-inflammatory hyperpigmentation.  It's difficult to say for sure without knowing what was used for the injections but in either case the best thing to do is to follow up with your treating physician and to avoid sun exposure to these areas. These often improve on their own with time but it could take months or longer.

It seems that the slerotherapy solution was injected under the skin outside the veins. This is unfortunate but can happen. The marks will take time but should resolve in 2-3 months.

It is unclear to me what type of injections were performed on you so it is very difficult to answer this question. I would definitely return to your treating physician for examination to recommend the best treatment for you.  Best, Dr. Green