Girlfriend sick, you are is a sample template you can use to write a letter for a sick friend.
When I heard you are currently under the weather, I became worried. You are definitely one of the people I care about the most. I will gladly inform you which medicine you can take so you can feel better. As an alternative, you can take herbal medicine so you won’t have to worry about side effects.
Hope you can update me about your condition from time to time. If you don’t, I will ask anyway. I won’t stop until I find out you are alright once again.