I’ve been in the form recently regarding an act of protected sex I had with a SW on October 12th. I did a 4th Gen combo test+full panel 46 days after the exposure in which I came back negative for everything. My only concern is that I read that false negatives for HIV can still happen before 51 days, is that true? I’m concerned because my partner and I last had sex October 30th and November 3rd and lately she’s gotten some acne, red dots around her eyes and and an itchy bump on her nose. She also told me today that she randomly around 8 PM developed intense back pain. Could I have infected her with HIV? Should I retest? 

I had protected oral sex with the SW. No vaginal or anal penetration. 

Just to add her back pain was sudden and according to her bad enough not to be able to walk. It was lower back pain, and she said there was nothing she’d done that would have hurt her back. 

Welcome back to the Forum although I'm unsure why you felt the need.  As described in your earlier interactions with Terri and Dr. Handsfield  you were told that the encounter with the CSW in October you described did not put you at risk for any STI, including HIV.  Two days ago, Dr. Handsfield replied "...you really didn't need testing -- it's fine you did it for the reassurance you will gain from the negative result, but there was no point in it from a risk standpoint. You don't say what you were tested for. HIV definitely will be conclusive and so will your negative syphilis blood test.'  I agree with the assessments of Dr. Handsfield and Terri so now it's unanimous.---

Understood. So 4th gen tests are absolutely conclusive at 46 days? 

Yes.  Believe your results.  EWH---

Got it, thanks for reassurance. One last question, that’s a little unrelated. How effective are lambskin condoms at preventing the spread of STDs? (ive never tried them before, a friend recommended) 

Lambskin condoms are more expensive than latex and, because the come from animals theoretically could allow the virus to pass through the poses in the condom material.  In all likelyhood they would reduce risk for viral infections but not totally eliminate the risk.  They would be effective for preventing bacterial STIs like gonorrhea, chlamydia and syphilis---