You could try using a clarifying/detox shampoo once a week in case you have some build up from the hair dye and the products you've been trying, Redken do one called Cleansing Cream or Toni and Guy Detox texture shampoo or I'm using Lush Big shampoo at the moment.
They can be quite stripping (especially the Lush one) so you'll need to alternate with a moisturising shampoo and a really moisturising conditioner afterwards. (For conditioners I like Redken All soft, Aussie 3min miracle and Garnier Ultimate Blends- the orange Argan oil one. The ultimate Blends honey shampoo is a good moisturising one. Although my hair isn't really damaged, I get dry ends, so you might find others that work better for you.)
Philip Kingsley Elasticizer is excellent. It's quite expensive but you get a few uses from the smaller tube if you want to try it out. Still ££ but not as much.
Avoid ever using a brush. Use a wide toothed comb instead. Microfibre turbans are brilliant for getting your hair two thirds dry before you blow dry, so you can reduce the amount of heat you use. Avoid straighteners etc if you can.
Eat plenty of protein rich foods, fish, chicken, avocados, nuts and seeds. Think about adding a zinc supplement to your diet as well as an omega 3. If it's something that's happened fairly quickly, perhaps a check for vitamin deficiencies at the GP might be helpful? Iron levels and vitamin D3 can affect hair, skin and nails. As can hormonal changes.
Whew that was long. Hopefully there's something in there you might find useful anyway. Good luck. I'm very certain you can get your hair back to a state you're happy. 