HELP! Transmission problem

Ok, this is way over my head and no clue where to start as this is something that's beyond me.
Have a '90 auto, 4.0. I've noticed a few days ago that when I put my transmission into lowest gear, it doesn't react as it usually does [slows way down] Noticed today that for some reason when I put the trans power switch on, seems nothing happened, and no light on the switch. Noticed the fuse was blown for it as well. Blew a second one sometime after replacing the blown one this afternoon.
Checked the switch, and the light on the swtich is fine and not blown at all. So what is wrong? Haven't been messing with anything. I added a small amp wired straight to the battery, but my trans problem stated before that. I also seem to have lost power to my cigarette lighter I use for accessories. Don't know if they're related or not, but not thinking so.
Could there be a relay blown somewhere possibly? What should I check to pinpoint what's out of wack. Driving I"ve not noticed anything wrong, except when I put into low gear, and thinking about it now, wonder if putting it into that blew the fuse, since I did do that since changing the fuse.
TIA

Just tried something on my way home. Put the trans in 2nd and drove home, as well trying the power switch. Didn't blow the fuse, so whatever is causing it, is pointing to the low gear only that is blowing the fuse and more than likely not letting the switch work.

Anyone?