Sedentary guy, sweating bullets

Hello, I've been very sedentary in the last 4 months or so, I worked out on averege like once a week and I've been working from home, so basically I walked very little during this time. I also gained like 12 kg. Now, when I start walking, even at a low pace, after 2 minutes or so I start sweating a ton on my back, face and head. Then if I stop, I start sweating even more for like 10 minutes. What's weird is that I went out last week to workout, I walked for like 15 minutes at a fast pace and I didn't even break a sweat. Is it because I'm super out of shape and basically walking very little, or I might have developed hyperhidrosis? Has any of you been in my situation? Thanks guys!

Not unusual for sweat for sweat to start pouring once you stop your workout.
You may or may not have HH. Sweating for the most part is normal with any workout.
The part of HH that most of suffer is when we are not working out and our body overreacts to general stimuli. Our bodies react as if we are in fight and flight mode.

Not sure what your overall history is in regards to doing any exercise prior in your life.