I have 3 cats, brother & sister 6 year olds and a female 1 year old.  My six
year old female, Cleo has been acting very differently lately.  We have only
had the 1 year old female, Bella for about 5 months and everything has been
fine between them (after the first 2 weeks).  Now Cleo is growling and
hissing at Bella when they lay together.  Everything will be fine, they will
clean each other and for no reason that I can see, Cleo will attack Bella,
swatting at her several times then growl and/or hiss and run off.  I've also
noticed that she seems to be gaining alot of weight.  I know she is not
pregnant.  She has always been tiny, weighing 3 to 5 pounds and now she seems
to weigh about 8 to 10 pounds all within the last year or less.  She does
seem to eat better than before and doesn't seem to puke as much.   She seems
okay toward her brother, Kodi most of the time.  Sometimes it is like she
can't see them very good and it scares her yet her favorite toy to play with
is a laser light (which I am very careful with to make sure it doesn't get
into her eyes).  I guess I was just wondering if anyone knows anything that
could be causing this.  I'm just afraid that she has a tumor or something
because I had another female cat about 10 years ago that had a tumor and she
started out getting mean and hiding all the time but I can't remember if she
gained weight.  Also before we got Bella she was and still is very spoiled.
Could she just be jelous of Bella because Bella is very needy and
affectionate?  Any suggestions would be well appreciated.

Thanks,
Tammy