Sharp pain

Hi

Just wondered if anyone else gets this? Seem to be doing much better on symbicort lungs feel nice and open and can take nice deep breaths. Finally my peak flow is back near my pb. Trouble is when I do it's painful like a sharp stabbing pain at the bottom of each oft lungs it eases when I start to exhale. Anyone know why this could be or get this? Have got appointment with nurse tomorrow but just asking for experiences. Thanks