When I have a decision to make I've used several techniques to help me see what I want to do.
I've made lists. Pros/cons, costs of one over the other, stresses of staying verses the stresses of changing, and more. These help me see more concrete issues that are effecting the whole thought process. This often helps calm my mind. I can mentally go over the lists and resort it, add something, discount something else that I thought was important but doesn't seem that way anymore.
I've done stream of thought writing, getting all my fears and frustrations out, onto paper, and I wrote and wrote and wrote until my arm was falling off and wishing it would fall off from the pain. Then I read some of it, felt it creeping back in, so I took it and burned it. Then it was gone. My mind was clear.
I have gone to a therapist and told them I had to make some decisions and felt like I needed a sounding board, for just a couple of months at most. It's their job to be that sounding board and see where your blocks are and what you can do to move forward. That worked really really well. I'm really really audio so even hearing myself telling someone all about it helped me to figure it all out. I'd have never got through it if I hadn't heard it for myself..lol.
Then there is always just going to a quiet place, if you pray just bow your head and talk out loud to Him. Tell him your fears and frustrations. Ask for help. Then sit and listen. Be open to thoughts and promptings of the Spirit.
If you don't pray then go and do a similar thing but sit quietly and say it all out loud. As if you were a friend listening to another friend. Then you can hear it and think on it like you're helping someone else. That often gets "us" out of it and we can see solutions much clearer.
Finally, if you have an old professor or business friend that you can confide in, someone that works in a similar field, someone that is able to 90% see your dilemma, talk to them. Ask them for their honest opinion. Ask them if you need to take more college courses, update your skills, get a master's degree, etc...what can you do to make yourself more valued as an employee.
Find out what they think you need to do. I don't know what field you're in so I can't say if I think you'd need to go back to school or not but I don't think it's a bad idea, if only continuing education sorts of classes.
I think leaving your job is hard. It's the devil you know. Leaving it then going to another place that might be worse is terrifying. BUT it could be completely wonderful too.