I'm new to the clarinet and I'm having trouble when I hit the lower G. It's getting very frustrating.
Sometimes I can get it, then I'll lose it, the clarinet will squeak and I have to start over. It sometimes
works when I start on 'C' and then work my way down but it comes and goes and I can't figure out why.
By "lower G" do you mean the lowest G? There are four G's within the normal range of the clarinet. If you can play any notes at all on the clarinet, the lowest G should not be difficult. HOW new are you to the clarinet? Are you sure your clarinet is in good repair? Do you have a teacher?
A common cause of this sort of problem is that the link between the lower & upper joints needs adjusting which is easily rectified by a technician. Also ensure the two joints are accurately aligned when assembling or this can cause the problem.
I had trouble with my lower G too than with the high third register. It was my embouchure. My embouchure still causes me trouble with the third higher register, still, but I am improving. I have to practice high notes first and then mix it with lower registers. Practicing scales helps too, but start with the hardest note and work your way down scale. Can you play the lowest G or anything higher then the G? There might be something wrong with your clarinet.
What I did when learning higher or lower notes was to slur from a more comfortable note slowly up or down to the new note and hold it for a while to learn the embouchure.