I'm looking to strengthen my abs, as they're very weak, but there's a hitch; a lot of exercises which are said to be great I can't do without my lower back 'clunking' about whilst performing them and sometimes without getting pain. To give you an understanding of what causes this, it seems to be anything that changes my hip angle, ie
-hanging leg/knee raises
Even if I just stand straight and bring one knee up to my chest and then lower it it can make my back 'click.' And by click I mean I can both feel and hear my lower back make a dull 'bumping' noise. If you were to gently tap a table or wall with your knuckles, that's the noise my lower back makes, albeit slightly muffled.
Does anyone have any idea what the hell this could be? I have anterior pelvic tilt due to several muscular imbalances, one of them being my abs, which I think play a part in it, but other than that I'm clueless.