Mastoiditis

My daughter who is now 13 months old had contracted mastoditis at 10 1/2 months. She had to have emergency surgery asthe bacteria had really gone through the mastoid bone heading towards her brain and it had travelled through her blood.  This infection came on fast and furious and the only sign we had was fevers and a bad cold. She never played with her ears. Only when she had a fever longer than 48 hours and then swelling and redness in her face and behind her ear I rushed her to the hospital. She had a month long stay at the hospital and 2 months of IV treatment.
All that said - we are always very concerned when she has a fever or anything related. Over the last few days she has been cranky, not drinking as much and playing with both ears.  The "bad" ear now has a bit of redness behind and a small hard ball/lump right on the top part of her hear - just behind.  She does have a scar from the surgery but this I have never noticed.....We have an ENT appotinent next week but should I be concerned??
Thank you in advance for your help!!!