Dry eyes were one of the first symptoms I had. In fact, before I was diagnosed with BEB, my ophthalmologist began treating me for dry eye. I use an ointment each night at bedtime and preservative free drops or gel during the day as needed. I also had my lower puncta cauterized to keep the tears that I did have from draining (tried plugs and they wouldn't stay in). Some on the BB also have problems with blepharitis - maybe they will post too.
The link below is to a research report which discusses dry eye as an irritant which can play a part in developing BEB. This may not apply to you, though, as your dry eye appeared later.
It is also possible that Botox has made the problem worse.
Virginia in AL
Related link: http://www.blepharospasm.org/evinger97.pdf