Why do I keep getting so many spots?

It has been nearly 5 months now and I keep getting 2 or 3 random spots on my face. I have never had spots before and now my skin just doesn't clear up....when one spot disappears another one will grow in another place. They are not even small pimples, they are actually quite big with pus and they hurt if I touch it, even just to put cream on. First, my doctor prescribed me with Duac and now he's given me Epi-duo cream to apply on the spots and Tetralysal 30mg antibiotic tablets to take once a day for 2 months....I have been taking these for nearly 3 weeks but I'm still getting new spots. I have a wedding in 6 weeks time and my skin has lots of marks on it and yet more spots just keep appearing. I'm really stressed out because of this...please can anyone help?