Teenager needs some help

This last year was very hard for me, I lost my pet as soon as lockdown began, and I got a new one only to get really attached to him, and he ends up dying some months later. I’ve got pains all over my body, tight chest, keep seeing in my head the sun setting by the lake as I die. I barely talk to my friends anymore, I try but they aren’t very interested. All this is really taking a toll and if someone could help I would really like that.