I had one after Alfie and bless ya it isnt nice is it.
what happened with mine was i stopped losing blood and then 2 days later i started losing clots real big ones and i told my W who said that it "wasnt normal but my womb was contracted fine so just to wait till it stopped"
i left it wasnt seen and was rushed to hospital a few days later with a real bad infection that had it not been treated then it would of developedc into TSS, so i was really poorly with it.
They didnt say anything about it affecting fertility but i would of thought that they would of mentiond it had that of been the case!
They told me they believe the reason for mine was because my womb contracted very quickly, in fact too quickly which meant that it didnt give my womb time to naturally dispose of all the loss i was supposed to which meant it all got condensed squahed and was taking longer to be able to "come out" naturally so in a sense it was going stagnant and starting to rot
sorry if tmi,
my womb was fully contracted by the time my MW came round on day 3, and still she never checked my pad (which they should)
the anti biotics should work really quickly mine did and by 3 days later i had started to feel better,
I hope you do feel better soon i can sympathise as it really is painfull and makes you feel unwell.