There are experts in the med tent that would be more qualified to offer suggestions.  If you have tried gel forefront cushions and arch supports, I could only recommend looking at other issues that might assist with stability and reducing the amount of pressure.  So, I would say consider some quality (thigh high) compression socks with extra ankle support and an upper foot cushion pad. 

Also, look at the structure of your shoes and consider whether or not they represent the best model, so if there is a rounded toe in combination with a narrow toe box, that might add to the discomfort, for example.  I am not suggesting that is the case, but switching out of the Asics in training would be a good idea anyway to avoid placing strain on the same areas over and over again. 

Wishing you all the best.

Morton's Neuroma?

Len

Have you ever assessed (either on your own or with someone) your running style/form?  I wonder if there is something you're doing with how you run that may be putting extra stress on your feet.  Two examples just to make the point:  If you're a heel striker that takes long strides, maybe the foot is "slapping" down onto the ground extra hard?  Another:  Do you bend your knees much when landing?  As I've messed with my form I've been amazed at how different running feels with more knee bend.  It puts your body in a position to have the whole body absorb the landing, and not focus the energy in a smaller part of the leg.

Jim

These might be kind of long shots but I'll throw them out there anyway:

• When you land with your forefoot, do you leave your calf relaxed so that your heel can come down?  Some people keep their calves tight to prevent the heel from touching, and that can be bad.
• Since you're running in pretty conventional shoes they have a reasonably high heel-to-toe drop, which means your heel can't come down as far as it was "designed" to.  I wonder if that's causing your forefoot to take the brunt of the landing force.  Another way to say it:  If your foot/heel could get lower to the ground (using a show with a lower heel-to-toe drop) I wonder if the landing force would be spread over your foot more - and also enable the leg above the foot to work better.

Grasping at my $.02.

Jim

Wanttorunmore-I hope you finished MCM.  Although your event is over I thought I would respond.   Your case sounds challenging. Good to hear the shoe change is helped.

Inthe long term I would suggest looking into your stability, strength and endurance throughout the core. Despite 'core' training being a common mantra for running injuries in my 15 years of coaching if still find most runners I work with do not regularly have the movement patterns they need to prevent injury, especially with marathon training. 

I'm not talking about crunches either.  To get an idea of the exercises that would be ideal for runners of all abilities to be doing check out the link below to my instructional videos. The injury prevention and strength videos are the type that would improve running specific core strength.

I know it's your feet but I hope you consider getting expert help in reviewing your mechanics and strength.

Finally my intention isn't to promote my coaching, but if you are able to get to the Portland area our Runners Workshop would be perfect for you. http://www.crpusa.com/p/runners-workshop.html

http://www.crpusa.com/p/instructional-videos.html

Best wishes!