Freaking out! Please help

I had some spotting like once a day last week like i was going to start my period.. not sure since the iud has only been out since August 8. So I found out Friday I was pregnant!! Couldn’t believe it so I went to work(in a hospital lab) ran my labs and had a hcg quant of 75 and a positive urine test.. so Saturday I had some light spotting again a bit more than earlier in the week and on Sunday it was gone. I reran labs Sunday and quant number was 171 so it’s going up.. today I have had lower back pain and this evening a bit more spotty.. should I worry or just try to stay calm? Please help thanks!!!