Should a previous employers insurance be paying my LTD first or would I be paid through medical EI then apply to their insurance company? Their insurance company told me to apply after my EI runs out, however the pay is different and they advised they’d cover me until my doctor ok’s me back to work. Whereas EI medical leave is only approved for so many hours.

Typically, LTD benefits have a 'waiting period' (the time between when you go off of work due to your disabling condition, and when you're eligible to receive LTD benefits). Often, this can be anywhere from 70-120 days, so EI is typically used in the interim until your waiting period has lapsed. That said, you can ask your insurer directly for more information on this period so you have a better understanding of the timeline you're working with
If you have any further questions or concerns, please contact our disability specialist, Rebecca, and she can help (at no charge) - rebecca.stap@stlawyers.ca