Glad to hear you are on the mend.
I am getting over a bout of Post Concussion Syndrome. I have been advised not to attempt to grapple until the New Year.
The medical advice I have been given is that I can grapple once my PCS clears up, but if I suffer another concussion again (even a mild one) I could do serious damage, and have long lasting problems. For me, it isn't worth the risk.
The only place I would attempt to grapple again is a non-competitional Judo club about 25 miles from where I live. It teaches a more traditional kind of Judo, and it is a lot safer than other Judo clubs I have been to. Although they do Randori, it isn't stressed as much as in other clubs. They spend a lot of time on breakfalls and learning waza and teaching the principles of Judo.
You have to make up your own mind as you know though. If it were me, I probably wouldn't. If you do go back though, here is my advice:
1) No randori competitions.
2) Work on relaxation more. Maybe look in to something like yoga. Translate what you do in Yoga to what you do in Judo.
3) Do lots of work in your breakfalls. You can never practice this enough!
4) Get a group of training partners in class that understand what you have been through, and will help you build back up. Avoid people who are there to prove something/treat you like a wrestling dummy.
5) If you really want to compete in Judo, try Kata competitions.
6) If you can do the Yoga thing, ask your teacher about Ju No Kata. It is a fairly gentle kata that loosens people up, physically and mentally, in Judo. Here is some more about it:http://www.judoinfo.com/kataju.htm
Video of Ju No Kata (1st Part):http://www.youtube.com/watch?v=95nSU5UX-j4
7) If you want to learn the principles of Judo, without actually doing the Judo, try the Shodokan Aikido place. Shodokan is the competitional style of Aikido. Though it isn't as rough as Judo randori, it is still tough going:http://www.fayettevillemartialarts.com/classes/Aikido/Aikido.htm
Some food for thought. To conclude, if you do go back to Judo, you are going to have to change the way you approach it IMO.