medication - prothiaden

I've been on prothiaden for 3 months, because I started feeling anxious.  Was involved in terible tradgedy 14 years ago when I was put on Effexor.  Terrible, headaches and total insomnia which didn't resolve. Stopped and was drug free until recently when Doc. put me on prothiaden as I wasn't sleeping.  I love it.  Have been able to sleep 8 hour nights (not since 14 yearsago) yet feel energetic all day.  Only side effect seems to be a bit of night sweating.  
Am wondering if I can continue to take this indefinitely.