Garth and crying

Happy Friday everyone!!  I hope everyone's week has been great and you are looking forward to your weekend.

Clint and I had a date night last night.  It was our first official date night since Ava Quinn arrived.  What did we do might you ask?!?!?!
Source

This was Clint's first concert.  I know, that is crazy.  It was an early Xmas present for us him.  Garth put on an amazing concert.  He played all of his best hits.  His wife Trisha Yearwood came out to sing with him and OMG her voice is AMAZING!  She sings live just like she would on the radio.  That is the sign of a beautiful voice!

My sister and her fiance Ava-sat last night and I checked in to see how things were going.  Ava has been having a rough time the past few nights.  She is the happiest baby I have ever seen.  She gets a little fussy when she is hungry, needs changing, or is tired, but the past few nights around 6:30ish until 8:30ish she just cries.  Well, last night was no different.  That is why I checked in and my sister said she was a little fussy.  Ok!  Good deal.  I can relax a little and continue to enjoy the concert.  Well, when we got home we found out the truth.  She was crying so bad my sister thought something was wrong with her and my parents came over to help.  The tried everything from changing her to playing to trying to feed her a little.  Finally, she got to sleep.  I felt so AWFUL.  I hated they had to see the "Jekyll" side of Ava that she has been portraying the past few days.  I felt guilty for going off and having fun while she was home crying.  Clint helped me relax and remind me that my parents didn't mind coming over to help.  This is some phase she is going through.  We waited 4.5 months to have a date night.  Plus, it was great birth control for my sister and her fiance!

We researched and there are a number of things that could be going on with her. 
-Teething
-Overtired
-Gassy
-4 month transition is big for babies
So, no definite answer.  We are going to take each day and thank God she is only like this for a couple hours a day.  I can't/don't want to imagine what parents go through with babies with Colic who cry ALL OF THE TIME.  No wonder mamas go through post partum depression and need drugs to get through.  It is awful listening/watching your child cry and you can't for the life of you figure out how to "fix it."  Being the fixer I am, it is horrible.  The whole notion of "crying it out" that all of the books teach in my opinion are crazy.  We will  let her fus, BUT when she starts really crying, uh-uh no way.  We will go get her.  It is torture to "let" her cry to me.  I know this is a big debateable issue, but that is my opinion on the situation.  My heart can't cope with the "cry it out" method.
Thoughts?
Advice?

No workouts the last couple of days.  Wednesday, was a chance of freezing rain, so we stayed home to play it safe.  Last night was the concert and tonight is my great uncle's surprise birthday party.  But come hell or hight water, we will be at the gym tomorrow morning!  I think I might try the Body Pump class. 
Any advice on the body pump class?
Is it worth it to try?