[censored] LAG, stop raising my blinds

[gh9801]

PP 30+3. Blinds 100/200

CO is LAG and dominating the table. He has been steadily accumulating chips, raising about 20% of pots. ~13000 behind

Hero has been tight but raising a lot in position, with stats probably around 12/10. I have also been letting LAG have his way. I have only shown down one hand, AA, after I had raised 2.5xBB (which is standard for me). stack ~3700

All fold to CO who raises to 900 (standard). Button folds, BB is very tight. Hero in SB has 77. What's my action and plan?