Feeling Tired and Week Always. To do.

Hello Sir I am feeling tired and week always no energy through out the day my knee joints hurts in the morning and after getting up slowly slows down.. but leg pain remains.. I have fear about my health this is happening from 8 months.. I ad been doctors did all the test all test came normal my ESR is 20 slightly higher trigercylindes 210 and vitamin d3 13.7 I took uprise d3 3 months but still I feel weak and tired. don't no what to do.. doctor telling that it may be anxiety.. but I always have muscle cramps and joint pains sometimes normal.. but worry is always there.. don't no what to do.. daily I get up with with worry then my tiredness and weakness starts.. no energy throught out the day kindly help me regarding this. I am teacher profession.. height 167cm weight 67kgs age 36years