2 or 3 years ago I had to have our septic tank pumped out because I thought it was backing up. The local guy that did it showed me a couple of things about maintaining the system and other than using RidEx to keep the tank activity up, it went in one ear and out the other as I was in the middle of several things when all that came up.
About 3 weeks ago, SWMBO was taking a shower and said the drain was backing up. I tried plunging it and that didn't work, so I called the local drain cleaning guy. He told me that I was number 4 on his list at that point and he'd see me sometime that afternoon. By 4:15 I still hadn't heard from him and I called him again. I was "next". I decided to look into it a bit more before he got there and decided to work backwards from the septic tank into the house. I dug up one of the septic tank lids and was greeted with a big clog of ..... stuff... clogging the pipe from the house into the tank. EWWW!
I immediately called the septic tank guy from a few years ago and told him that I needed the tank pumped out ASAP. I went ahead and uncovered the second lid to save him the trouble and had visions of needing my leach field replaced. When he got there we chatted for a second and then he opened the second lid and looked in it. He said "Yup, I thought I remembered you having an effluence filter. Don't you remember me telling you about how to clean it every couple of years?" He pulled the filter out and the tank immediately started draining into the leach field! While his son was pumping the tank, we flushed the filter clean with the garden hose and put it back in place. 20 minutes and $300 later I had an empty septic tank and a clean effluence filter!!
So, check the exit end of your septic tank to see if there's any sort of plastic filter at the exit. From the top, mine was about the diameter of a soup can with an arrow indicating the exit direction. If so, pull it out and hit it with the nozzle on the end of the garden hose. That might be an inexpensive fix to the issue. Let me know if you want/need me to post a pic of it.
The septic guy did tell me that if you needed the leach field roto-rooted to find someone that specializes (or at least has a lot of experience) in doing leach fields and that you didn't want to have just anyone with an auger sending that through the drain pipes. You might want to check with a local tank cleaner to see if they can make recommendations.
Good luck!!