Can Small Reddish Pimple On Penis Be Symptom Of STD?

Hi Doc. I am a man aged 40, 175m tall and 106kg by weight. Have been sexually inactive for the past three years following my divorce. Just a week before Christmass I decided to give it a try with my new girlfriend. Barely a week afterwards, I started feeling pain in my lower limbs, backaches, headaches and would feel cold during high ambient temperatures. I then noticed a painless small redish pimple on the foreskin of my penis and the left side lymph nodes had swollen.



Could this be a form of STI and if so which one. Secondly, if STI, then howcome because we had protected sex. Any chance of contracting HIV virus if the symptoms are for STI. Whatever is the case how best can I be treated.



Thanks



Aagostinho