Aggressive cat behavior toward self

We have a spayed, female, seven-year-old indoor cat, Schroeder, that
has always had small episodes of apparent stress where she
aggressively chases her tail, hissing and growling. In the past year,
a number of life changes seem to have escalated Schroeder's behavior:
We moved to a new home and had a baby. She had a chance to adapt to
the new home before the arrival of our son and she seemed to adjust
fairly well. However, now that we have a very vocal seven-month-old,
she has become increasingly more aggressive towards herself. She
chases her tail still but has begun to screech when she does it rather
than the old ways of simple hissing. This has escalated in the past
few months.

Most recently, we moved the cat litter into the basement in
preparation for our soon-to-be-mobile son. This seems to have put her
over the edge. Schroeder's episodes have moved into the night and are
interrupting our sleep to the point that we find that we have to lock
her in the bathroom to get a decent night's sleep. In addition, our
second cat stalks her. She corners Schroeder under the bed or in
rooms that have only one exit. We scold her when we catch her but
since we aren't always there, we can't always prevent it.

It seems like some of Schroeder's episodes occur when our son is vocal
or crying which makes me think that he is causing her stress.
However, as I mentioned before, she also screeches in the middle of
the night when our son is sound asleep so I am uncertain as to what is
causing these particular episodes. I understand that cats are
creatures of routine and all of these factors have contributed to
disrupting her routine but it also seems that she is not readjusting
over time.

We took Schroeder to the vet and all of her tests determined that
there was nothing physically wrong. We even went as far as giving
both cats parasite medication to be certain that they weren't the
cause (recommended by our vet). We are doing our best to give both
cats individualized attention everyday and play their favorite games
with them.

We really don't know what to do. The vet suggested that we might be
able to put her on Prozac which may have to be our next step if we
can't figure out an alternative solution. Any ideas or suggestions
would be greatly appreciated. Moving the cat litter back into the
house is not an option since we live in a one-floor condo and have
limited space as it is (and I also don't think that moving the cat
litter is the main issue here).

Thanks!