I took that antibiotic for a skin infection I had 12mths ago and I actually ended up with a major guttate flare up of my psoriasis and ended up with 85% coverage! So I don't like it at all as it's the first time I have had a reaction to abs.

I guess you could ask if there are any alternative abs you could take and let him know of your concerns over this one, but generally they prescribe abs depending on the infection and that may have been the best one for the job. Also you have to work out whether the pros of having the cyst gone (if it is causing you some pain etc) will outweigh any possible side effects from the abs - because don't forget that not everyone will have side effects from them - you could be absolutely fine.