I'm 25 next week and waiting for doctors to call me to tell me what investigations they want to do so I know the feeling. FIT test came back >400 and the other sample showed possible inflammation as well. Had blood test at doctors and I'm also anemic which I had no idea about as I just put my fatigue down to having an 8 month old baby and going back to work after Maternity leave. If you want to push for a second opinion to put your mind at ease then 100% go for it. I'm a massive Hypocondriac so I always seek a 2nd and sometimes even a 3rd opinion.