Can I use Fibonacci with S/R and candlestick together at a time?
Sure, its called confluence, where multiple signals are overlapping, and can help to strengthen your bias. A common trategy is trading the 50% retrace on a trending pair, and entering the trade on a candlestick pattern like a pin bar, engulfing bar, morning/evening star, etc.
Yes you can, Fibonacci is one way of analysing the charts but it is good to have multiple indicators and determiners.