My shower has been producing less water and now barley any water is coming from my shower head.

Only the shower? Probably a mineral clogged screen or restrictor. Remove the head, soak in vinegar ovetnight and make sure the holes are open. Flush with water. With the head removed check the water flow, the diverter may be clogged too.

Remove shower head, clean filter inside, reinstall

Milo

Remove shower head, turn on water and see what you get. If you have a full stream, then the shower head needs cleaning, and that's as simple as soaking it in a solution to cut the mineral deposit build up, as was said before.

Is this just a shower, or do you get the same thing in your tub as well?