Trouble running after a few weeks off

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Ended my HS basketball season several weeks ago. Had about a month of MS V'ball then about a month off. I walked regularly and jogged a little in the off time. When fall soccer and then basketball season ended I was getting up and down the field and court with no problems at all. Now my Spring soccer season started last Monday and I have been so stiff and my knees have been so sore (I have arthritis in both) and my lower back so tight that I'm running so much slower than normal. I can ususally keep up with the HS boys without working too hard, but am working hard just to keep pace with the girls. Also I am so stiff and sore afterwards. I've never had this happen before. Have any of you? Any suggestions or thoughts? I'm real concerned!