In the past I ran with compression songs after I had calf problems. It went really well, HOWEVER, when I took them off and started running without again I got injured immediately. No idea if it was coincidence or if I trained my legs to depend on them that they weren't self supporting anymore.
For other medical reasons I now started running again with compression socks, however, I try to get every other run done without and hope to drop them asap for everything.
It feels so great to finally get a diagnosis and the treatment starts, doesn't it? I think I am 'running' a couple of weeks ahead of you in terms of that. Since April I am just going from test to test, since September I am treated for blood clots (PE), and now 2 weeks ago they found the underlying cause and I am allowed to very easy jog again. Parkrun this Saturday was my slowest ever, lowest ever age grading run, but so great to have it done.
As for coming back to were you were, don't try it too hard. Be better than last week, that way in time you get to where you were before you notice it, without being frustrated all the time, and much more rewarding. And accept the random drop in performance without explanation as a blip. 2 years ago I stopped running with an ankle issue, was suddenly fat an slow and went out every run with the old pace blowing up a mile in. Once reviewing that issue of mindset I ran comeback PB and later proper PBs again. I am planning the same this year. By December 2016 I am running a PB . Any PB ( but 2 miles indoor doesn't count).
MRI is a good step. I got mine 6 weeks ago and it has thrown everything upside down. I went from a non-treatable heart muscle decease to 'don't know exactly, but not that what we thought. I have at least a PE, but it might be something else, other tests coming and to be waited for. Basically, you don't know what it is until you had an MRI, and even then you can just exclude some things.
The annoying bit is the wait between appointments. I got my MRI about 10 weeks ago, 5 weeks ago I spoke to the heart muscle specialist, now I got an appointment in Dezember for the 1st consultant again.
I am quite jealous you are still running a bit. I ran for the train last week, and we hit Putney before I started to breath normally again. Went through the 'scared to drop dead' but if I would be at risk they would keep me in the hospital.
My hope is to start running again with a double parkrun on January 1st. Started golf in the meantime.