Worried about my cat

Dad had said something about my cat, of about 2 or 3 years of age at this point, was coughing and sounded to him like it was a person yesterday. Today I came home from work 5am-2pm and let him in, and I heard it for the first time. He only coughed like it a few times and then it went away. Originally my first thought was, "ohhhh it's getting colder out, maybe it's because of his winter coat." But he isn't acting normal now that I am watching him closely, he usually is a very energetic and very talkative cat but today he is silent and is lying around ever since I let him in about 40-50 minutes ago, is it because he maybe be tired from being out all day or is something wrong with him? Also I don't know if I'm looking too far into this but he seems to have a lump in the stomach area, kinda right in front of his back legs.....he is a very skinny and small cat so I'm wondering if that is normal to be feeling or if I should be more worried. Please any and all help is needed and appreciated! Thank you in advance.

His he eating? Drinking? More or less than before?

If your cat is acting strange and not himself it is always good to take him to a vet to get looked over and get bloodwork if necessary. It is better to be safe than sorry.

I agree with Love my calico.Don't wait.Something is wrong.they hide things very well and by the time you decide it's time to go to the vet it's too late.Coughing could be a  number of things.The belly another.Pls make an appt.asap