u/Phillyyuppie

Water coming out of the 2nd story bathroom tub spout is HOT no matter how I adjust. I turned off the hot valve (behind the tub) and turned the cold on but it's barely coming out. Feels like cold water isn't rushing through the pex like it is with the hot water so I suspect it's not related to the valve body (?) since the issue appears to be happening before that. Any way to troubleshoot? And is this something I could handle myself or should I call a pro? I'm fairly handy.

Should not cold water pressure is fine in third floor bathroom, 2nd floor bathroom sink, and downstairs. This is an old philly townhouse.