hi doctor , one of my friend had a oral sex with call girl , while doing tht thier one cut came on his penis and its started bleed , later that girl told tht she had gums problem asitsteeth was broken recently , now my friend had done 4 hivtest , in past one month , and result is negative , can thier still be any ;possiblity of having hiv, though he dont see any sytoms accept some time pain in shoulder