There is really not that much to fitting if you are trying to just get comfortable on a bike...If the bike is too big for you; usually getting a shorter stem, moving the seat down and forward a little will solve most if not all problems. Just do the inverse if the bike is a tad too small for you. If you are looking for efficiency that is a whole different story, then you would need a professional fitting. This is especially true for TT& triathalon athletes as they need to be as aerodynamic as humanly possible while still being comfortable.
What exactly is your issue? We might be of some help and save you some bucks. Although this would be no substitute for a "professional fit", I am confident there are a number of different peeps here who can help you out...
I am going to take a stab here and guess your bike is larger than it should be which is causing you to overextend yourself to reach the bars. This is causing 2 things; 1)You are keeping your arms straight and tight(which is a no-no as they need to be relaxed and bent at the elbows to absorb the road shock), 2)You are leaning too far forward to reach the bars(Which is causing your back pain). You can get a shorter stem with a little more rise which will move your bars higher and further back. If you are still uncomfortable my next suggestion would be to get a different seatpost, with less setback. After that if you are still uncomfortable you can replace your cranks with shorter ones, which will enable you to lower your seat even further. An Ideal fit is where your back is straight at a comfortable angle, relaxed and slightly bent elbows while still getting an almost full extension of your knees.
With all that being said, I hear Get-A-Grip has an awesome fitting crew. I heard nothing but good things about their fitting services...
I went to Get-A-Grip on Irving Park three years ago inquiring about getting fitted for purchasing a Waterford road bike. G-A-G did personal fittings on site @ the time but, since I was dead-set on buying a Waterford, G-A-G set me up for a fitting appointment with Waterford @ its factory in WI. I took a weekend, stayed in a nearby B&B, then showed up at the factory in my cycling attire, and parted with my $150 for what amounted to a two-and-a-half hour session.
In short, the best $150 I've ever spent on cycling. The Waterford people made me get on the fitting bike and put me through my paces - fast riding, slow riding, riding-out-of-the-saddle, etc.. They took almost every conceivable measurement I could think of and then some. So much so that when I picked up the finished product at G-A-G, took it on its break-in ride, then back to G-A-G for adjustment, the shop guys only had to do a minor tweek of the handlebars and seat height - otherwise the bike fit me perfectly.
Your results might not match mine but before I did this, I was dead-set of the opinion that getting fitted for a bike was a waste of time and money. I have decamped from that position since taking my first ride on my Waterford. Spend the $$$ for the fit - you'll come out ahead in the bargain.