MRI of the foot is a piece of cake. You do not have to go all the way in. If they offer you headphones with music, take it. It's VERY noisy. You have to do your best to hold still. The foot will probably be in a boot-like thing. Good luck. Like you, I had terrible pain in my left foot... had been building and changing sites for 10 years. I had tried orthotics, cortisone shots, physical therapy,... Xray was negative; but an MRI showed a posterior tibial tendon. tear

I'm off to surgery in 10 days. Hope you get some definitive results. Undiagnosed pain is worse than diagnosed pain. If nothing else, it proves that it's not all in your head and that's affirming.