Multiple pains; pregnancy?

I forgot to add that, I have actually already been to the doctors about it however the doctor said if the test came back negative it will be correct. However I feel like I need to go back because I still feel so unsettled.

*I’m going to book myself in at the doctors AGAIN

Basically for like the past 2 weeks I’ve had a bad back and in the last few days I keep getting pains in my ribs and boobs. I did a pregnancy test 2 weeks ago and it came back negative but I’m still paranoid that this might be the case. I’m going to book myself in at the doctors but I’m scared they won’t take me seriously if I say I think I might be pregnant but I did a test and it came back negative. I just want to have a scan to be 100% sure that I’m not.
I’m just more paranoid cos my friend recently had a baby but she didn’t realise she was pregnant because she had periods, no bump (the bump went towards her back which resulted in her having bad backs) and when she thought she could of been pregnant (she kept having a few symptoms of pregnancy) and did pregnancy tests, all the tests came back negative.

Does anyone have any advice for me?