Poor credit/getting a loan

Let me start off by saying I'm not exactly sure what our credit score is, but i have a feeling it's dropping because of being late on a lot of bills/car payments. (Due to my husband switching jobs, making less during his probationary period)

We bought our first house 2 years ago, we were approved for a certain amount and still bought a house $100,000 less than that amount.

Anyway, we're getting caught up on bills now (almost there!) But at the end of the month, after paying our bills, mortgage, car payment (just one, his truck is paid off) we just manage to get by. We haven't saved any money. We are living paycheck to paycheck. I'm sick of it.

Our plan is to sell our house, downsize and get a smaller/cheaper house so we can start saving money and be able to actually have extra money to do things!

Does anyone have any advice on how to better our credit or possibly get a loan and out of this house before we create a bigger mess.

*renting is not an option at this point.