I also forgot to mention that it is very important to detox while you are on the diet. The best way to do this is with a sauna and NOW fiber 3 powder 1 tblsp. with great plains bentonite clay - 1 tablsp in 6-8oz of water before bed away 1 1/2 hours away from any supplements (daily). These two things are very important. If you do not have a sauna, a hot tub or hot bath with epson salts will help as well.
Low ferritin levels can be caused by the candida as it feeds off of iron. The way you can get your levels back up with out iron supplements is to take lactoferrin. Some researchers suggest lactoferrin might play a role in solving global health problems such as iron deficiency and severe diarrhea. Lactoferrin helps regulate the absorption of iron in the intestine and delivery of iron to the cells.
You need to look into candida overgrowth. It can cause the muscle pain and tendonitis. I have had both of these conditions.
Try going on a sugar free, dairy free, complex carb only, no simple carbs like pasta or bread and gluten free for a few weeks to see if you feel better.
Candida is an imbalance in your colon and needs to be addressed. It happens because of the use of birth control, antibiotics and poor diet. You can have candida for a long time and not know you have it until robs you of to many vitamins. It can make you deficient in iron, calcium, vit.D, b vitamins and much more.
I started taking d-ribose 3 times a day, Udo's 3*6*9 oil blend daily, probiotics 30 bill. twice daily and a multivitamin that has methyl b12 and methyl folate in it. You should also try taking magnesium citrate 100mg with each meal if you can tolerate it.
I don't know about the ferrous, but i do know about general body fatigue and pain. This can occur for many reasons, and sometimes it's temporary and sometimes it's not. See your doctor, and ask for a mild muscle-relaxer (non-narcotic is best).