Cat Throwing Up since Yesterday

Yesterday morning around 5am, I fed Mittens NB Turkey canned and he threw it all up after 10 minutes. 

At 8 am he had some water, and few minutes later he threw up again.  This time clear with some foam.

He slept until 2pm and had some purina ur wet sprinkled with fortiflora and he was fine, through out the day.

Last night he had a good appetite and ate purina ur wet with fortiflora, about 1/4 can.  Also some purina ur dry as a treat about 6 tiny kibble pieces.(I use the purina ur dry as a bed time treat.

This morning again, he had vomited his 5am feeding of some fancy feast turkey.

Had another small liquid throw up at 8am.

He wanted more food so I gave him some purina ur wet with a sprinkle of fortiflora and purina ur kibble.

I see his urine was half the usual amount so I'm a little worried.

Could it be a hairball? or something else.  The only difference is I started him on purina ur canned on feb 3rd .  In 1/2 tsp amount mixed with his fancy feast.  I also started fortiflora the same day to make him eat his new canned purina ur. 

I have always fed him small meals about 3-4 hours apart through out the day. 

I'm just worried about this vomiting.  Dehydration is my main concern. Could is be serious?

Vomiting in the morning is often caused by too much stomach acid.  I see your kitty is on a prescription diet, is it for his kidneys?  Often kitties with kidney issues will also have issues with stomach acid.  

Many people will give a treat or a very small meal first thing in the morning to soak up the excess acid.  Some people give Pepcid. regular strenghth not the complete to help with stomach acid.  

If the treat or very small meal first thing in the morning doesn't help I would ask your vet what he thinks is going on.  If possible you could also feed his last meal of the day later also.

He's on a urinary prescription diet.  He had a uti in early December and has been on Purina UR dry.  I also feed him Fancy Feast classics.  I want him to eat mostly wet so I purchased the wet Purina UR.  And am slowly mixing it with his fancy feast pate.

He had a blood count on Dec 9th and the Vet said his kidneys looked great.   I was thinking it could be a hairball, since he's alert and his usual self. He is a long haired cat and I don't give him any type of hairball remedies. 

Mittens eats small meals through out the day.  I've been never been able to put him on a schedule.  He's a very pushy cat and when he wants his food, he keeps opening kitchen cabinets, until he gets his food. 

He just had a big drink. The Purina UR makes him really thirsty.