thatrunninggirl you need to have blood tests for haemoglobin and ferritin level not just take iron tablets.
There are some people who can easily end up with too much iron in their blood and they get similar symptoms to people who are iron deficient. Plus some other vitamin deficiencies start of by mimicking the symptoms of iron deficiency.
Also during your treatment you need to the level(s) checked to confirm the iron supplementation is working. If you don't you could end up like one of my sister's who had to have an emergency blood transfusion.
Either way when I had low ferritin I had to take twice the dose of a supplement like spatone for about a year there as when I've had low haemoglobin I've had to take high doses ferrous sulphate for anything from 8 weeks to a year.
Go and speak to a sports physio. If required the physio will refer you to your GP to refer you to the correct specialist.
I personally wouldn't bother with a GP first unless you know they are interested in sport.
I am only saying this because I had a GP who could diagnose neck/back muscle problems caused by sport simply because he did the sport, and another who couldn't diagnose a severe vitamin D deficiency even when it was causing bone problems. In the first case I was told to go to a physio in the second case a nurse diagnosed me. I was advised not to do strenuous exercise by some medical practitioners, while others were telling me to do some even though I could just about walk.
I live in an area where there are lots of cycling, running, tri, football, rugby etc and a few rowing clubs. There are also a couple of sports science orientated unis nearby though I've never used them.
So if I want a physio, etc I ask someone who will normally recommend one they have used themselves either privately or due to their club affiliation. ( I am a running club member so get all the ads but still ask for a personal recommendation.)
The only time I could not ask someone for a recommendation was when I needed a podiatrist as none of my local friends' and acquaintances had used one at that time, so I used someone mentioned on here.
If you don't know people to ask I suggest you state your area and issues, and hopefully someone on here can recommend a few people.