I suggest to change the current FA/Doctor cooldown into a cumulative cooldown, like the Gathering one. For now, you heal once/you have to wait a few minutes. This could be changed - you can heal as many times as possible, but when the timeout reaches 10 minutes then you have to wait for it to decrease. I also suggest to cap the FA healing, because when you can heal 3 times in a row, then it shouldn't be +100-150 hit points each time.
The cooldown (10 minutes) could increase with the % you have in the skill (the higher %, the higher cumulative cooldown limit), and the capped FA healing could be increased if you have spent many skill points in that skill. For example:
50% in FA: Cooldown = 5 minutes, healing capped at 20.
100% in FA: Cooldown = 8 minutes, healing capped at 50.
150% in FA: Cooldown = 10 minutes, healing capped at 80.
Etc.