Slipped discs pressing on the spinal cord can have very similar symptoms to MS - they could certainly cause problems with your bladder and feet - in fact, anything below the level of the slipped disc.
I do have MS, but was initially investigated for a slipped disc, because of identical symptoms. It was only when they were surprised they didn’t find one that suspicions were raised of something else.
However, the thing with slipped discs is that they NEVER cause problems above the level of the disc.
If you think of your spinal cord like a motorway, with your brain - the command centre - at the top, instructions go from the brain down, to tell parts of the body what to do, and feedback comes back up, to tell the brain what that part is doing, and where it is, and how it is feeling (hot, cold, painful, touching something etc.)
If there is an “accident” (slipped disc or MS lesion or whatever) blocking or part-blocking the motorway, traffic North of the accident can still get to and from your brain OK. But traffic South of the accident may be restricted, held up, or (worst case) not get through at all (the latter would result in complete paralysis). But there is simply no way an “accident” at the far end of the motorway (lower spine) could affect the command centre (your brain) at the top.
Therefore a slipped disc could cause all the other problems you describe, but NOT the ones with memory and concentration. Remember, your brain is still in proper two-way communication with everything above the site of the “acident” (slipped disc). It is only below it traffic could be disrupted. It doesn’t work the other way round - i.e. signals from the accident travel back up and mess up your brain. That can’t happen. So if something is not functioning right with your brain, that cannot be caused by a slipped disc.
It is just about possible it could indirectly cause it, because anxiety about the other symptoms might distract you from what you’re supposed to be doing, which could give the impression of memory and concentration problems, even though it’s just worry, and not actual damage.
Either way, I think you need to go back to the doctor, if you haven’t already. Say, for the sake of argument, it was the slipped discs, and the rest is just worry? Do they mean to just leave it like this?