Can your previous employers to rehire you? You did a good thing by leaving the job as mental health is important as well.
I feel your situation...
This must be difficult to cope with.
Start applying for new jobs and contact your old company too.
You will definitely land up somewhere good.
Btw what kind of problems are you facing here?
Sometimes it's anxiety that makes the job stressful. I left a job for the same reasons too. But holding on to the present one coz I know how difficult the situations are and I learnt my lesson to never leave a job widout having another one in hand