I'd suggest you get your radiator serviced 1st.
This would include removing the radiator from the car, getting it's top removed & the innards cleaned thoroughly. If there's a crack or leak, it's better that it's discovered this way than while you're driving.
If things go well, the entire process would be done in a matter of hours & cost yo no more than RM100 (non-KL price though ).

Flushing alone might rid you of the problem for the time being, but it'll come back sooner than you think

Get it done once & get it done right