How long have you known the lumps are under the skin?
There is a good chance that the lumps are fatty tumors called lipomas. These are not cancer, but do get bigger over time. There is no reason to remove them unless they are causing a problem (getting irritated from pressure when the dog is lying down or under a leg for example).
Your veterinarian can tell if they are lipomas by feeling them and sometimes by using a needle and syringe to get a small sample and make sure it is fat.
Did this answer help and do you have follow up questions?
Most lumps in older dogs that move under the skin are lipomas. It is possible that they could be something else or that your dog's heavy breathing is unrelated to the lumps.
Is it hot and more humid than usual where you are? That could account for heavier breathing particularly if she is not in air conditioning. Respiratory diseases and heart disease can cause breathing to be difficult, usually more than just a little heavier than normal.
Look at your dogs gums over the canine teeth. They should be pink (not blue-gray, white or dark red). If they are pink, there is enough oxygen in her blood.
Then press on the gum with your finger for a second and notice how long it takes for the gum to go from white to normal. It should be about 2 seconds. This is a test of the circulatory system.
If these are normal, she is OK for now. If the heavy breathing continues, a vet visit makes sense. Unless she gets suddenly worse, it should be able to wait to normal hours.