My car started making a really loud squealing noise towards the catalytic on the rear of the engine today, it only makes the noise as I accelerate and it's causing me to lose power, any suggestions?

Possibly exhaust escaping at the manifold pipe gasket due to blocked catalytic converter... Have a helper rev engine while you listen at tail pipe for normal exhaust flow... Cat tap converter with rubber hammer to check for broken catalyst 'rattle' inside converter.