Period cramps after egg collection and transfer

Hi guys, totally new to forums but hoping someone might have shared in what I'm experiencing. We are currently doing ICIS treatment had egg collection last Sunday with 10 eggs 7 of which were mature enough to fertilise. 5 made it to 2nd day so they wanted to do day 5 transfer with blastocysts on egg transfer day we had 1 top grade embryo and 2 suitable for freezing so we were really happy. Here's my question, soon after egg collection I started getting period type cramps I asked my nurse she said its quite normal and nothing to worry about, but they have carried on after embryo transfer and it truly just feels like my period is coming? Anyone else experienced this and still had positive result blood test day? Thanks :-)