Looking at the ingredients list for the sleep walker supplement you've been taking, there can't be any more than about a gram of phenibut in those things at MAX. This is a negligible dose that shouldn't result in any side-effects if used in the manner you described. I recommend simply quitting use immediately and scheduling an appointment with a psychologist/psychiatrist. The symptoms you describe sound like those of an untreated anxiety disorder.

Do NOT buy pure phenibut to taper since you don't have anything to taper off of in the first place lol (the person that posted that clearly didn't read your post very well/at all.) A good psychiatrist will get you on the proper meds and feeling better in no time. Good luck and message me if you have any further questions.