you don't say how much thyroxine you're taking, i would agree that you should go back to the gp, it can be difficult to get dosage right. as someone has suggested, you may be taking too much and i think that is effectively creating hyperthyroidism, a more complex problem than hypothyroidism.
i have under-active thyroid and although my appetite didn't increase like you describe, (i was thin before diagnosis and remain so, which is 1 reason i think my doctor took so long to figure it out......that and the fact that he was rubbish!) but from being lively and active became incredibly tired and i remember it took about 4 months of taking thyroxine for me to feel remotely human. i take 100mcg and now, 18 months after diagnosis have twice yearly blood tests to ensure that i am still on the correct amount. persevere and insist that your gp helps you to find the right dosage.
i had itb problems last year and can sympathise because at the time i too felt it would never go away. i'd agree that sports massage was essential to my recovery, it will hurt (a lot!) but is worth it. as has been suggested try to get someone by recommendation, maybe through your club. boring, but true, is building up your running really gradually as part of rehab, and for me, strengthening the quads with visits to the gym. not rocket science, i'm sorry, but hope this offers some sense of light at the end of the tunnel!
i beg to differ.......i've done windsor and marlow for the past couple of years and i'd say that windsor, the old course and the 'new, faster, flatter course (??)' of 2001/2 is merely a warm-up for marlow. marlow is tough! but having said that, i look forward to it all year!
ps yes, there i am writing this from the psychiatric ward!