Hello OP.
So sorry you're experiencing hair loss - it's very distressing and sadly, there's no quick fix.
I recommend your first port of call to be the GP, just as you're doing, to check for an underlying cause. Please make sure you get sight of your results as NHS guidelines for what's 'normal' doesn't always tally with what's really normal!
I suggest a close look at your ferritin level, which is different from your HB level. If it's below 70, low ferritin could be the cause, as it does cause loss, specifically at the hairline.
Hair lotions and potions can stimulate your scalf, but normally because you're simply massaging them in and encouraging blood flow to your scalp. Don't believe the hype, but use one if you want to keep your scalp happy! It certainly will help it's overall health.
Your GP may offer you Rogaine or minoxidill. Please consider this option carefully. I chose not to use it, because as soon as you stop using the product, your hair will still fall. I felt it was more of a sticking plaster, but the choice is yours.
And please remember that hair has a fall/regrowth cycle of three to four months - so even if you are taking steps to improve things, it may take a while.
I hope that helps you. x