TMD/TMJ, help with pain?

I've suffered unbearably for years with what I thought was sinus problem nobody could fix. Recently learned it's all from TMD; I clench my jaw without realizing it. I've changed almost every aspect of my life recently, (what I eat, sleeping position, got a wedge pillow, etc.) and I'm still in terrible (albeit less, I admit) pain. I know that a nightguard can help me at night if I get one, but I'd like to know... Is there anything I can do or use during THE DAY, when I'm awake, to prevent myself from clenching my jaw? 1) I clench without realizing it. 2) I fear that perhaps I "over-correct" when I try consciously to avoid clenching; I have no idea how wide the normal "rest" position of the TMJ joint is. I need to have something that keeps it both from being clenched and also from being opened too wide. BTW, my dental insurance is pretty decent, but I can still expect to pay 20-50% of my dental cost (depending on procedure). Even that percentage may prove beyond my budget.
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WHAT YOU NEED IS A BRUXISM APPLIANCE TO STOP THE CLENCHING AT NIGHT WITH THE PAIN BEHIND IT. AN N.T.I. BRUXISM APPLIANCE WILL DO THIS. SEE THE LINKS BELOW. ONLY YOUR DENTIST CAN MAKE YOU THIS.
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