Chancroid or any other serious STD?

I noticed an ulcer on my testicle, so I went to a dermatologist, and took meds for around 10 days. That ulcer is almost filled. But today I noticed another big one and 2 small ones on the tip of my penis. As of now I am taking homeopathy for that and tomorrow again I'll go to the derma to talk about it. I am really not sure if it can be herpes or any other STI. My partner has never done anything sexual with anyone other than me, that's a 100% and neither have I. We've been together for 1.5 years, so I don't know what it can be. I am really tensed how it is possible to get an infection. We mostly do oral and I don't know how is it possible for infection to occur. I am going to ask the doctor for bloodwork tomorrow, and we'll see what it can be after the report says. taking levofloxacin as of now. please help!