Cat has diarrhea and straining

My poor cat Pudden has been very ill with asthma over the summer. We finally got her to a place where she was doing well, but today she suddenly became very sick.

This morning there were multiple piles of mushy poop in her litter box along with a large amount of urine. Later in the day she began going in her litter box i think to poop some more, but nothing or very little liquid stool comes out and she then proceeds to vomit clear liquid from the straining. This has happened several times.

She has urinated today a few times, but both were smaller than usual amounts. She is not eating. She did drink a little on her own this morning. I have been syringing water so she doesn't dehydrate. She is also very lethargic.

I am going over everything in my head that could have caused this. Yesterday I introduced a new silica gel litter by Dr. Elsey for asthmatic cats so I immediatly changed back to regular clumping litter after this morning incase that had anything to do with it.

We also gave her beef treats yesterday which are new, but she has had them in the past without problem. For the past few days I have been giving her a cranberry supplement to help with uti's. She was treated for a uti recently and I wanted to prevent anymore. She also gets pills with pill pockets which I know can cause diarrhea in some cats and dogs.

She eats friskies dry food and I have been supplementing with various fancy feast canned food recently.

I will not be giving the cranberry relief or pill pockets any more incase one of them was the culprit. The beef treats wil be discontinued as well.

I am waiting to see how she is in the morning. I plan on calling the vet and letting her know what is going on tomorrow. I just was looking for a little comfort or advise until morning. Has anyone experienced or heard of cats straining after episodes of diarrhea and now nothing comes out? I thought straining was only with constipation. It's scary the way she vomits right after every time.

Fecal impaction is one possible explanation.  That could explain the leaks of runny stool, her straining to defecate, and her vomiting.

She has been having large formed bowel movements everyday including the morning before this started so I don't think it's a blockage in the bowels. The only thing I have noticed is her stool has been a very light yellow color. She is on prednisolone and aminophylline for her asthma and I just chalked it up to the medications.

I am a little worried it could be a urinary blockage of some sort, but she has urinated a few times today although the amounts were smaller than usual. I just wonder because of the recent uti. However when she strains it really looks like she is trying to poop rather than pee from the amount of pushing she does.

She has been sleeping these past 4 hours and has not been to her litter box since. I hope that means things have settled down and she is just tired. I'm hoping it's not from weakness. I have been giving her water, but holding back on food until things slow down. I really hope she is better in the morning. She has suffered so much recently and this setback is heartbreaking.