Hi, I've too have been struggling with my voice - having foolishly 'forced' the volume a couple of weeks ago and the first thing I suggest is rest. Secondly practise slow deep breaths in through your nose (for a count of 7 - 8 or as long as you can and out through your mouth for 15 - 16 or longer, using your diaphragm! Make a conscious effort to sound a quiet note for part of the time you exhale or use a sssssssSSSSSSsssssss sound and 'feel' that the sound is 'on the breath' rather than forced from the throat!! It took me a while to 'separate' the wrong breathing from the right, and it'll take a lot of effort to keep doing it the right way - good luck.
Drink water, water or water!! Boring but best. Try it luke warm.
Have a long hot bath and inhale the steam. Avoid really hot drinks.
Much of this info came from a speech therapist (not a voice coach - as I've not gone that route yet).
Whatever - best wishes,
Hazel.