Welcome to the forum and don't worry, what he is doing is perfectly normal for a bird that was handicapped and is now able to use his main mode of transportation - think of a small kid that has had his legs tied and is now free... he is not going to be calmly walking from one room to another, he is going to be running around the house like a maniac!
As to his hitting his head, etc., well, that's because he has not had the practice he neeeded to master the art of flying. The thing with birds and flight is that although flight is necessary for good health (respiratory system partly atrophies when birds don't fly - not my opinion, a scientific fact) and for self-confidence and emotional wellbeing (flight being the ONLY predator-avoidance mechanism that birds have with the lack of it causing chronic stress and anxiety), it's one of those things that starts as a mere reflex with the hatchling flapping his wings but needs practice in order to develop the muscles, stretch the tendons and simply learn the techniques. I have birds that are fully flighted now but because they were kept clipped for a long time, they are very clumsy fliers. They all get better but the longer they have been clipped, the clumsier and weaker they are and some of them never quite get to really master flight.
I would strongly urge you to reconsider clipping him again. It's really quite unhealthy for them (both physically and emotionally) and it doesn't prevent their getting hurt or lost, quite the contrary, it's pretty much a death sentence for a clipped bird to get lost - and they do get lost and much more often than people realize. Much safer to have a bird that is good at flying and which you can teach to come to you on command (and you are already half-way there if he always flies to you!) PLUS, you have a Jenday and they usually become loud and constant screamers when unhappy and the little ones are always unhappy when clipped.