horrendous vibration and thudding!

[Rhodesbears]

Hi,

My beloved RAv 4 51 plate delveloped an intermittent fault around 6 months ago, has now become a severe problem that no one can seem to pin down.  

It manifest as, from cold and and approx 2 miles into a journey a stange rythmic thudding grown louder and louder, seems to come from rear offside, first time It happened was convinced it was a puncture, stopped, inspected, no flat, re started journey, no noise, everything fine!  IN short this has become increasingly frequent. We have changed the propshaft joint which was fine, have checked disks and handbrake, garage has checked it out too though of course it didnt 'perform' when they tested it.  

Definitely heat releated, brakes now squeak for first 50 yards from standstill, there's also a very loud clonk now from off side rear when cool. Always (so far) the problem fades away if I drive on... Could be my imagination  but steering feels heavier.   Convinved this is brake related, something binding or loose.  Disks are not warped.

Any suggestions gratefully received, 

Helen