First of alll, have you talked to your doctor about your past experience with sulphur based drugs? Has he answered all your questions and does he still say you should be okay taking this drug? If yes, then I see no reason not to take it. If not, then maybe you need to call your doctor and discuss your concerns. After all, that's what he is there for

Second, anything that you take internally will not interfere with your topical application of benzoyl peroxide. In my case, I took Minocycline for about 6 weeks while on the CSR and the antibiotic helped me tremendously. I stopped taking it because I had an allergic reaction to it. Nothing serious, just some red itchy patches on my arms and chest. Anyway, I think you should be fine.
Good luck!