Prolapsed disc and torn plantar fascia

Brief history:
39 yr old male, very physically fit since 19 years old. I've been a cyclist from 19 to 34, competing in time trials with PB's of 22-42 for 10 miles and 59-36 for 25 miles. Competed in road races, MTB races, cyclo cross races, and been on training camps in Majorca etc.

switched to running for the past 5 years and have pb's of:
5k 17-54
5 miles 29-08
10k 36-56
HM 84-08
20 miles 2h13
marathon 3h12
all achieved in last 24 months

Started weight training last summer which was based around free weights and compound exercises mostly.

i tore my left plantar fascia in March this year which I was seeing a physio for but it was taking a lot longer than the 12 weeks he had thought it would.
From May this year i was also getting back problems down my left side which I thought was sciatica as I suffered from this about 8 years ago.
it got progressively worse and I've seen the doctor for pain relief, a chiropractor, a practitioner of the Bowen technique and now an Osteopath.
by August I got so bad I couldn't even drive the car or even sit at my desk for longer than a couple of minutes.
i requested an MRI and got the following results:

"MRI lumbar spine: Sagittal T1, Sagittal T2 and Axial T2 of lumbar spine is performed
The lumbar lordosis is preserved. there is multilevel degenerative lumbar spine disease is noted.
for the purpose of reporting I am assuming the lower most largest disc at L5/S1
L4/5: there is a circumferential disk bulge causing no nerve root compression
l5/S1: there is a large broad based left paracentral disk and sequestered disk causing compression upon the left S1 nerve root"

can I improve from this point and get back to regular running of 50mpw and make an attempt of a sub 80min HM at 40 next year and generally keep the fitness I've been used to for 20 years?