Answer:
John had a stroke and is having difficulty sitting and walking. The medical professional he should consult to improve his physical abilities is a PHYSICAL THERAPIST
Explanation:
A physical therapist deals with medical conditions that has to do with the bone, they are other-wisely called PHYSIOTHERAPIST. The physiotherapist would work on the difficulty mr John is having in sitting and walking, also drugs that enhances bone effectiveness would be recommended in order to hasten his recovery, also some walking and sitting aides would be employed to ensure it helps him to recover in shorter time.
