Animal Welfare Professionals

My 7 year old pit mix ,Thumper, has been nothing but an angel since bringing him home a few months ago. He has always though suffered from a touch of separation anxiety. The separation anxiety has caused him to bed a metal crate to the point of no longer shutting while breaking out. Also digging carpet, nearly destroying a door, and chewing things. His anxiety also has manifested when he has to really use the bath room and we finally go out. He barks and it seems he looses all sense in these moments. Never aggressive but clearly anxiety. I work from about noon to 8:30 at night and he stays with my mom during that time. In the past few days he has gone from showing the raucous behavior on the occasion to literally every time I take him out. He barks non stop, darts here and there, and sometimes jumps at me. My mom says she experiences none of this. I have already been told to see a trainer and plan to see one with videos of what happens but am having to wait at least another two weeks before I’ll have the money. My fear is the behavior getting worse and taking an aggressive turn before I can get an appointment. And also I just want him to be happy and healthy. I should note he has received heart worm treatment and is in crate rest. He has been for about two weeks now. Any and all help is appreciated! Thanks!

Truly, the best thing you can do is receive professional help from a behaviorist AND a veterinarian for anti-anxiety meds, especially during heart worm treatment. 
I would look into food puzzles, Kong toys, brain teasers, anything that works his mind during his down-time. "Find it" games, snuffle mats, anything enriching. Reduce his meals, and give him several enrichment items with bits of food in it throughout the day. Good luck!

Also, start with teaching him "Four on the Floor" and use high-value treats like hotdogs or chicken. If he starts rearing, stop and wait for him to settle. The moment he stops or pauses, give that high value treat. 
Here are some resources: https://www.sfspca.org/resource/alone-time-training-game/

https://www.clickertraining.com/how-to-teach-your-puppy-not-to-jump

Keeping in mind lack of exercise your dog can have right now: https://www.clickertraining.com/node/3493

Hi,    How is he doing since you posted? Can you video his behavior so we can see what he's doing, or is it too difficult because he's out of control?  I'd be happy to chat if you want some 1:1 support until you can get an appointment.  I'll send you a message.

Sheila