With the release of 9.3.4, Apple made it impossible to use the vulnerabilities used for the jailbreak which worked on 9.3.3. That's certainly the reason why you're experiencing these problems.
Since Apple isn't signing 9.3.3 any more, it's impossible to revert to it. The only software signed by Apple for the iPhone 4s, is 9.3.5, which also can't be jailbroken.