Chest pain when exercise

Since months until yesterday, i always go outdoor for a walk, with akathisia and withdrawal i walk normal(as a string puppet) and after 30 steps, chest pain, then i rest two/three minutes on a wall and restart 30/40 steps, and become lightheaded;
this chest pain comes similar as a amount exercise gives chest pain, a reflex, a bad reflex which my kind of walking maintains;
if i continue to walk so "quickly", i will still have chest pain in three years; i have to broke this cycle;
so i go out today as every day, and 30 steps after: chest pain; have to stop;
i changed my walk, more little steps, very less quickly, not so far as usual;
i had all time mild chest pain, and when it increase, i slow, stop, rest and restart;
outcome: less lightheaded, less chest pain = better; but it was not easy to walk slowly with inner restlessness(akathisia);
if i want to progress it is better to train the body to not have pains when walk;
I have not tried this in stairs, but i will in the future after practice;
i have constantly mild ribcage pain and spinal, but this is another thing;