Most likely you have a nerve being "pinched" by the muscle in your trap. This is very common, especially in the trap muscle. The muscle could be tight from training or tight from AAS usage. Some AAS make muscles tighter than others. Stretch out well and warm up slowly. Heat and massage will help loosen the muscle up so that it puts less pressure on the nerve. This is very common, but for some people may keep coming back especially while on cycle.