If you have a medical condition, a landlord is usually legally required to make "reasonable accommodations" for you. Explain your condition in writing and provide a doctor's note. At the end of the letter ask for an apartment on the first floor, a chair lift, or permission to find another place.
Breaking a lease is possible provided the leaseholder is agreeable and understands the tenants medical reasons leaving. You'd better have your medical records that show your change of circumstances (distance walking and stair climbing restricted by your doctoreetc..) before you take any next step.
Then, the best thing to do is to contact your landlord and let her or him know that you desire to get out of the lease for good reason. If the tenant is upfront with the landlord, there may be a better chance he or she would be willing to help.
As for the definition of "soon" it is possible next April is considered soon by the new management.