If your hair starts to feel a lot thinner due to the hair loss then I recommend that you get to your doctor straight away. A whole number of things that cause hair to fall out; alopecia, fungal problems, even wearing ponytails a lot! Most of these aren't serious though.
I have long hair and use a lot of styling products which causes split ends, dryness etc., so it's normal for me to brush my hair and have a bundle of strands left in the hairbrush!
For the flaking scalp, T-Gel therapeutic shampoo is good. Try that. It's a bit costly but worth a go. It's more than just an anti-dandruff shampoo so may tackle whatever problem you have.
Alternatively, pop to Boots and speak to the pharmacist over the counter.