Uhhh help?

Hello!

Backstory: my husband has been gone since early June (military), so I haven’t had sex in months. My period ended last Tuesday. Today, just now actually, I went to the bathroom and when I wiped, there was a pretty good sized blood clot, and it was like I was fully on my period all of a sudden. This has never happened to me before, what should I do? I have no pain, but my stomach has been upset since Monday. There’s no way this is a miscarriage, since I’ve been inactive since June. Any help or advice is super appreciated. I don’t know what to do.