Posted twice here and might sound annoying, I took a finger prick test today 40 days post PEP at a local HIV clinic and it came negative. I had a DNA PCR test at 18 days post pep which came negative. I am experiencing a headache, stomach pain and feeling weak. Also I am planning to visit my doctor and have an Eliza combo vein blood drawn test at 45 days. Can my 40 days test change after 5 days when I take the combo test.