Had Cervical Fusion, Tender To Touch, Redness, Soreness. Had A Surgery. Allergic Reaction?

I had a cervical fusion a year ago and about 3 days later broke out with what looked like chicken pox on both of my upper arms but only three on each . They were very tender to the touch but never escalated to anything more. Then this past March i had some surgery on my back and the same thing happened on my upper thighs,again 3 on each thigh , one on my left inside ankle and 2 on my right outer calf. Again very tender to the touch. Two days later they turned into the size of a nickel, very red , and extremely sore. The on on my ankle burst open and was very painful. Was this an allergic reaction to something during surgery because that is the only time that I have gotten this. I do have Discoid Lupus and take Plaquenil as needed. The Doctor gave me predisone and things have healed but I still have a lot of redness on the ones on my thighs. Will this go away and what else could it be?