Hcg blood test at clinic today !!

I went and got a hcg blood test for pregnancy today at my local clinic and counted my last period as October 20th I would be 6 weeks along had bleeding for 4 days November 13th-16th that wasn’t normal for me so I decided to get tested but I left and stuff and 30 minutes later it was negative ofc but they are a clinic and called me back 3-4 hours later back to back 4 times I had no idea it was them until they left a voice mail and I didn’t answer took a nap and stuff and it was nighttime what could they want that bad to do that? What could it be about I went to my ob today she only did a pregnancy urine test it was negative and felt my uterus and let me leave 😂 she was ur typical let me look at u for 5 mins and get ur money ifykyk. But what could they want I mean it’s odd right? Their a clinic. They didn’t say anything in the voice mail but left 2 voicemails just to call them back but it’s to late now and they said for that part of the clinic it was women and nurses. Couldn’t have been a payment issue I payed before I left lol and have insurance!!