My female cat has groin lumps and drinks a lot. What's wrong?

Hi and thanks for using Petco Pet Education Center, formerly Petcoach! Sorry to hear about Fusspot. The lumps in her groin areas may be enlarged inguinal lymph nodes, abscesses, tumors, fatty tissue disease (steatitis), etc. Increased thirst has many causes and is usually associated with increased urination also (called Polyuria and Polydipsia). Causes include kidney disease, lower urinary tract disease, diabetes, infection (if not spayed consider pyometra or uterine infection), thyroid disease, liver/gallbladder disease, other endocrine/hormone problems, etc. I would advise getting Fusspot evaluated by your veterinarian. Your vet can take a detailed history, examine her, and then advise diagnostic tests based on those findings. Usually a minimum database is a good start (fecal/blood/urine tests and imaging studies such as x-ray or ultrasound. Once a diagnosis is made a sound treatment plan can be discussed and implemented. Good luck with Fusspot.