So, last night while I was peeing, I noticed a reddish area at the left side of my penis - at the lower part of the head and upper shaft - and whitish waxy, smelly stuff there (which I initially mistook for dried or flaky skin until I touched it). It's that that stuff that gets caught underneath your nails when you scratch your head. I didn't notice them before until I pulled back the skin of my penis (I'm circumcised, BTW). I washed the stuff off and when I looked it up online, it appears to be smegma. However, this morning when my penis was erect, the area was still red and when I touched the area, it seems to be a tiny bump, or crack, or fissure which itches a little bit.
Now, I'm concerned because I had unprotected oral twice, 5 weeks ago and 2 weeks ago and protected sex (same exposure from 2 weeks ago - we did however, reuse the same condom very briefly but quickly changed to a new one) and I just noticed it now. There's no other symptoms like discharge from the penis, or obvious blisters or chancre, sores or lesions. Just red skin, smegma and the little bump/crack/fissure that can't be seen unless I pull back the skin of my penis and itches slightly when touched. Skin irritation or possible STD?