I dont know what this is,but lately im getting these little bitty?

gnats flying around my room,i have my pets in here,two budgies,a dwarf hamster and a guinea pig, their cages are kept clean and free of uneaten foodstuffs,i dont know if this is my problem or the fact that our health care aide who ists and cares for my 90 year old bedridden mother,when she takes my mom outside in the garage for the air and sun she never ever shuts the dang doors and the fiies ans insects fly inside our home,and as the buggies come in the air conditioning goes out,what is causing this gnat infestation,the animals bedding or our aides carelessness??