Talk to General Practitioner on Thyroid Problem

My mil is 59 years old . She has had border line thyroid and she’s been taking Levothyroxine 25 mg. Lately the problem is that she’s not feeling well after she takes the tablet . She’s been having throat irritation and cough and breathing difficulties. We doubt that maybe her thyroid problem is resolved now and she’s healthy . I wanted to ask if that’s possible and what are the symptoms if her thyroid problem is solved? How do we know if it’s gone and if she should stop her medication ?

Ps- we know that we can only get confirmation through tests but right now we’re avoiding to go to the hospitals .