Side pain (under armpit)

Anyone ever have a weird pain sensation there? Especially when bending down. I’m pregnant so idk if it’s just worse because of that. But it scared me. I keep thinking I have a blood clot. (That’s my anxiety talking) I have had 2 CT scans done on my chest. Due to chest pain and my d-dimer being high (d-dimer is always high in most pregnancies) but they never see anything. So the doctor said this could be a musculoskeletal problem and mentioned costo. But that was a month ago. He never explained to me what costochondritis was or how it affects you. That’s why I’m confused. Cause when I look up costo it tells me that the pain for that is in the center of the chest. So idk maybe this isn’t costo?