Crying before bedtime

My 3mo baby is used to being carried and rocked to sleep. However recently, despite having ample naps and keeping to her usual routine and observing her awake period, she cries very fiercely when carried like she is in pain and refuses to sleep. Yet she stops crying and can even smile when we put her down (she doesn't fall asleep though and will still start crying if we leave her alone). We tried carrying in various positions but nothing works. Her tummy doesn't seem to be gassy and we have already made sure she's fed and diaper changed. Any idea what can be causing the crying? I only heard of babies crying when put down, not when carried, we are v perplexed..