It looks like it's at the seams where the leather spine piece is sewn. It's a 3/4" 5 star. New Scott Thomas saddle. Weird marks. We rode for about 30 min or so. 

im thinking too narrow?  Not sure. 

I hope the link works 

https://photos.app.goo.gl/KYzw2NMKK9SqHpHJ9

Well I cant get to the pictures, I have to sign in for some reason and really dont know what thats all about.

How about this

https://photos.app.goo.gl/KYzw2NMKK9SqHpHJ9

I still get the same thing, maybe for someone else it will work, I'm not really all that computer savvy so it could just be me.

I'm not a saddle fitter, but I've done some training with it.   That saddle doesn't look like it fits.   The saddle looks way too narrow, which is pushing the pad into your horses back funny. 

This is obviously a brand new saddle with very thick fleece under it.  If it were me, I would ride with just a navajo or a very thin felt bad or even wet the fleece before you saddle to get it "broke in".  If the pad you're using has a cut out at the wither, that could be causing those marks, which is another reason i'd recommend a navajo during the break in phase while the fleece is compressing.  There really no way to tell how this saddle fits your horse until the fleece compresses a good bit and the saddle sits down more where it's supposed to.    

Two people are telling me it's too narrow and too straight of bars for his back. So I talked to the tack shop and they will take it back. Yes it's new. I am returning it. I was using a 3/4 flex fit 5 star. One person said to try a double j #10 tree. Someone said try brazos. I'm not sure what to try next. Hopefully wherever I find one, they will let me do a trial 

Does your horse have a dip behind its shoulders Like this, this is my horse and a double J #10 fits him well. He has to have a saddle thats got rock to it and the Double J # 10 has the rock. 

Like the others have said, I don't think that saddle fits. #10 trees are for a butt high horse with curving of the back, and it does look like that's how your horse is made in these pics. 

I'm trying to upload pics  I'm not tech savvy sometimes lol 

Here is a not so good pic of him standing 

Yep, you need a saddle thats got some rock to it. The Double J #10 and I know the older Meleta Brown Freedom saddles have rock also. I know theres a few more out there, but the Meleta Brown and the #10 Double J for sure since I have both. And another saddle that fits him well is my Caldwell ProMax. 

Great observations!  I have my reservations about cutout pads-I don't own one anymore.  Camogirl, what pad and thickness are you using?

And also the fleece - yes, I've had a saddlemaker suggest wetting and even riding with no pad to break in the fleece. At least a couple weeks.

I'm using a 3/4" 5 star with flex fit (open wither) I love the flex fit on this horse, it opens up his withers and shoulders and frees him up. 

Can you look where the edge of the pad lines up - does it match up with the swelled lines on your horse?  Or maybe a little lower if the pad works your way down as you ride?  

If you really like the pad, there is a possibility of beveling the felt - making it slant instead of a straigt edge at 90 degree angles. I have done that in the past to eliminate an edge of pressure (it would vary depending on the horse and saddle I used).

You COULD ride with a different pad for an experiment to see if you get the same marks?(one with a solid top - no cutout at all on the wither area - or have you tried that? 

I think the tree is just wrong for him. I have my saddle placed farther behind than where the open wither cutout is. I think this is where it's pinching. Where the spine leather seams are  but I could be wrong