Hi , had stiff knee when running for a while now. Yesterday i went running up snowdonia, after about 3-4 miles i noticed a pain in knee , i kep going until about 15miles then it was really bad, couldnt run downhill had to walk(flat was bearable if steady, uphill noticed pain but could run normally). Today its slightly painful when walking and the longer i walk the worse it gets but pain bearable not taken anything. When i try walking upstairs or downstairs it hurts like shooting pains . Pain seems to be on front of knee left side. Any ideas what it is? should i just rest a couple of days? if i could run in 2 days with pain killers would that be ok or rest for longer until pain completely gone??
Thanks for any advice