the what if's can be very draining and creates more fear.
tho i understand how you would feel. and, i'm sorry you're going thru it.

to get mental control back you might try thinking of a plan of action.
what if my pain became unmanageable? what if i couldn't get up one day?
then think of solutions, whether it's a phone call to a dr, a medication, a mobility aid...you get my drift.

that always helps me feel more in control and i can let the thought go.