English Writing - I wrote this short story and I would like to check if there are any grammatical mistakes.

Dear Gregory,

I hope you are doing well! I’ve got some bad news. Yesterday I lost my pet in the park. I feel desperate, and I am already missing him so much. I can’t live without him. I tried to find him but to no avail. It seems as if he disappeared off the surface of the earth.

While I was walking in the park with my dog, some colourful birds chirping on a branch caught my eye. While I was walking towards them, I tripped on a large stone and fell. I screamed in pain, and my pet got scared and ran away. I hurt my leg, and I couldn’t run after my dog. After a couple of minutes, I tried to stand up and walk. I managed to walk, but I was limping heavily as my left leg was still hurting.

I searched the whole park called my dog over and over again. After half an hour, I gave up and decided to go back home. Today I am going to call the animal welfare to check if they have found him.

Your friend,

John