My Cat Is Straining To Urinate, Can You Help?

It could be a lower urinary tract disease (LUTD).  Or even blockage which can be a very serious condition in male cats.
There is also the possibility of crystals that can develop in the urinary tract and cause irritation and even blockage.
Your cat really needs to be examined by a vet.

A lower urinary tract obstruction is an emergency---your cat will die without medical attention if he is unable to urinate.  Have him examined immediately there is nothing you can do at home.  Lower urinary tract obstruction can be caused by bladder stones or mucous plugs that develop.  After your cat receives treatment for the blockage your veterinarian can discuss ways to manage and attempt to prevent this from happening in the future.

I think that you are doing the right thing here with your kitty. Keeping an eye on it, and seeing if the medicine is working. Sometimes it does take a few days before the medicine kicks in, but you are wise to watch out for kitty. I would take her Tues if it isn't better. Hope this helps, good luck to you.

Oh my god!! Maybe she has a urinary tract infection or it could be stones that happened to one of my cats. It ended up being gall stones.....take her to the vet as soon as possible