Our 12 week old male pup suddenly got sick last night before we went to bed. He was fun and energetic as always but I put him out to potty and when he came in he was breathing heavy as if congested and became lethargic. After a couple of hours he seemed a bit better so we put him to bed. He seems a bit better this morning but I am watching him close. He went out to do his business this morning, stool is good and while he seems better than last night is still not himself. Last night he sounded like he had a cold when he would breath, up until that minute he was fine, it just started when he went out, that fast. I was with him when we went out he didn't get into anything.It is cold out but we were only out 2-3 minutes max.