Running and breathlessness and constipat

As I start workout I got breathlessness like I didn't feel earlier. Like I am able to do work in my breathing but it feel like heavy breathing. When I start running my legs Start from the very first day. I will manage to run for 2-3 km a day but everytime my breath take more time to get stable as compared to my other fellow freind. And after workout I am completely exhausted. I have chronic constipation. So I just want a suggestion which doctor should I consult for my breathlessness, leg pain which don't go when I start running or it is related to my constipation. I need suggestion because in covid it's hard to go anywhere. Please if someone suggest me which doctor did I consult like ortho, pulmonologist ur cardiologist.