Help Please - Cat vomiting, not using toilet

Hi - I am hoping someone can help:

My cat has not done a poop in her tray for about 5 days, however as she has been going outside every now and again I assumed she was going out there. The last 2 days she has vomited up her meals, and it is as if it hasn't gone to her stomach yet as its just food and liquid.. it doesn't smell. As of today she has vomited a foam-like substance twice now. I am feeding her water with a dropper in fear she will become dehydrated, but her personality seems the same? I have given her a dose of cat laxative because I read that she may be constipated and hence vomiting; this is advise I got from the pet supply shop as well.

Can anyone give me any advise? I don't want to pay hundreds of dollars to take her to the vet if it is something I can fix at home. 

Thanks

There are many possible causes of vomiting in cats. It could be a hairball that's causing her to regurgitate her food or it could be something much more serious. The vomiting of foam sounds serious as does the fact that she's been vomiting for 2 days. Cats can't go long without eating. They risk fatty liver disease. She also could have ingested something toxic while outside. If it's normal for her to poop in her litter box at least once in 5 days and hasn't done so, that's another sign that something is wrong with her.

At this point, I think she needs a vet visit.

I think a visit to the vet is needed at this point. I just recently went through something quite like this with my cat, at first even the vet thought she was just constipated but it ended up being much more serious and she had to have surgery, which she sadly did not make it through, and as vball said, cats should not go that long without eating, and even with the eyedropper of water she could be dehydrated with all of the vomiting.

After having such a bad experience recently I would say it is best to get it checked out soon, its better to go there and have them tell you she is fine then to regret not going in later.

I hope everything turns out well for her!!
 

The first thing that comes to mind is an intestinal blockage.  I would want that ruled out ASAP.