Anyone else?

Hello all.  So I'm in a weird situation.  I am currently 4 days late on my period.  I took a test yesterday and 2 days before that as well (both negative).  My breasts are very sore and I've been overly fatigued for about a week.  About 5 days after one of the times my husband and I had sex, I had some dark brownish spotting and then it went away.  That was a little less than 2 weeks ago.  Implantion bleeding maybe?  Now here I am.  Late period and pregnancy symptoms but 2 negative tests.   Anyone else have negative tests that end up being positive?