bruised toenails, should I size up?

Hi, I've bought scarpa mont blancs, half size up from my street shoe size, worn them for 4 ice climbing sessions without problems and on the fifth I didn't lace them tight enough or maybe wore too thick a sock, and bruised both my toenails on left and right which I only felt on the way home at the end of the day. Then for like 3 months turned black and half fell off and took a year to grow back. I thought it was a lacing issue went out for the first time this season laced nice and tight at mid foot and up the ankle thinking it'll keep it from sliding forward and bashing toes, and after one climbing session on the way home felt it get sore and hurt and sure enough right big toenail was messed up again. My right foot is half size up bigger than the left, so I'm thinking I didn't size up my boots enough since it only happened on the foot that's tighter. Do you all think if i size up from 44 to 45 it'll fix it? Or is there some other issue at play. I cut and filed my toenails super short before climbing anticipating this possibility.

had a similar issue some years back and sizing  up solved it.

-Haireball

Bad fit ... My boots are sized up 1.5 - 2 sizes. First thing that goes is the original insole and it is replaced. That takes up 1/2 size. Then I usually wear nice thick dachstien socks and sometimes with VBL. That takes up another 1/2 size. That leaves a 1/2 size for toes wiggle room in my performance boots. In my high altitude boots there is another 1/2 size cause feet will swell at altitude. 

for performance you want the smallest size that doesn't leave you with sore toes. 

Improve the fit with thicker insoles! tighten the laces tighter right before climbing. Hopefully your boots have lace locks so the upper part of the boot does not have to be tight. 

If you have a lower volume foot you may be better off with LaSportiva.

I've had this problem in the past and two things worked to fix it: improving my footwork and insoles. When kicking, keeping my feet pointed up let's the crampon and heel take the brunt of the force, not the toes. Insoles help keep the foot from shifting in the boot, along with tight ankle lacing.

Definitely need to size up, sounds like your toes are squished together.

One thing not mentioned is your age; once you get into your forties, your feet start to grow.

I remember way back when I had to start changing out all my rock shoes and my favorite Scarpa Freneys

Not sure about your sizing question, but I have the same problem and always mess up the nail on my left big toe just as you describe.  Like you, I always cut it short as I can then round off the edge with a nail file.  Then, I tape the toe -- two pieces of tape "long-ways" -- ie. from the big knuckle on top, out the length of the toe, over the nail, and then around the tip of the toe and ending somewhere on the bottom of the toe.  Has worked so far to keep the damage to a minimum.

Update went from size 44 to size 45 Mont Blanc's. Same problem because my toe is still sore, it's super senstitive when i put the shoe one, now that i'm 2 sizes above my shoe size the problem with new shoe is still there. Turns out top of my toe pushes into the padding of the mont blanc's so if i take out the insole completly the pain goes away, so its a volume issue not so much shoe length issue. Will be trying nepal cubes next.

I had same problem with the MBs, switched to Salewa and all is good. Still use the MBs for glacier climbs and low angle ice. MBs are Super comfy until the ice gets steep and real kicking is required.