No problem using them at the same time, except you will have to reduce the dose of DermaTherm or Sustain since you wont have enough skin surface area to use a full dose of each product. Also, you can apply the Sustain to the gentile area, but don’t apply the DermaTherm down there… it will burn. Also, don’t apply the DermaTherm before bed. The hormones will mess with your circadian rhythm and sleep quality so make sure to use this product in the morning.
As for post cycle therapy, I wouldn’t suggest the DermaTherm or any 7-keto hormones. They can and do negatively affect the HPTA to a minor degree so they are something you want to avoid for PCT. Phosphatidylserine would be a much better PCT cortisol blocker
-Pp