When to see a physiotherapist / osteopath?

Hi,

I'm a 25 yo male researcher, who works sitting at a computer for probably about 10 hours a day. One thing friends and family have noticed is that I'm incredibly rigid (stiff), despite playing some sports (badminton mainly). For example if I do a forwards bend to try and touch the floor I am about 8 inches away (at one point I couldn't get past my knees but this has improved).

I was getting lower back pain, which I went to the doctors (GP) about. On their advice I took up swimming and this has helped, however I now have pain in the middle of the back. My back (middle and upper) click and "creak" a lot if I stretch. Is this the sort of thing I should see a physio about? I did do yoga for a while but it sometimes makes me so sore I cannot exercise for about 8 days afterwards (I have a tendency to over-do it I think).

Thanks.