Strategy changes every few month?

so here is the sum, i have a strat, that basically OB strat, i mark ob in 15 min TF and then take entry on 5 min engulfing, this start gave me 9.5% in dec-jan, but suddenly justafter feb started, it took away 6% from me and 1% more in march, why this happened, all was going good then suddenly this happened, now dont able to find what to do, wait for that stratergy to work again?