Lumps on chihuahua’s belly

They are hard moveable lumps when touched. I noticed the first one a couple weeks ago and the other one appeared a few days ago. What could they be?

Hello!  I'm afraid that breast cancer ( benign or malignant) is a possibility for lumps in this area, as can mastitis be in entire females.  Mastitis can be painful;  breast cancer is often painless but there are various other possibilities too, including skin lumps. It isn't a blue lights emergency unless there are signs I don't know about, but definitely worth a check over in the next few days if possible.