bug bites or syphillus?

Hello, for the second time in two months i have recieved 3 large bug bites, one on my neck, arm, and wrist. along with the bug bites i have also an open sore on the head of my penis. The sore looks alot like the pictures that i have seen of syphillus, the bug bites itch, the sore is uncomfortable. The first time this happend i saw a doctor and he said it was just a cancre sore, but i am worried, i have the same symptoms in the same exact spots for the second time. My groin area is extremely itchy and so are other random parts of my body, especially the spots where the bites are located.