This is an excellent question. You need to ask your lawyer as he or she is aware of the specific facts and circumstances of your case. You don't want general advice, you want the correct advice.
You should discuss these matters with your attorney directly. Generally speaking, a personal injury settlement will not effect Social Security Disability Income (SSDI). However, a special needs trust planning lawyer should be consulted to determine if the establishment of a special needs trust is the proper course of action in your particular circumstances. The transferring of the settlement into a properly prepared special needs trust may protect Supplemental Security Income (SSI) and Medicaid Benefits, if any.
Yes you do have to report income to medi-cal and any other needs based benefits programs you are on. (eg SSI). This money will likely disqualify you for some period of time until the money is spent down to get you back to the eligiblity guidelines. The spend down must be done properly. That means the money has to spent on certain things and you need to have proof of what it was spent on. You can ask your social worker or go on line and find out what you can spend on.
You need to postpone if you can, any expensive medical procedures until you have requalified.
If you don't report, you could get charged with welfare fraud, and you could lose benefits for an extended period. Years ago, I had a client with medi-cal and we reimbursed them as reqd. However the client didn't report the net she recd to them, and she got in trouble for it. Don't let this happen to you. If you handle the spend down properly, you will only lose eligibility for one month, and you can use the money for some beneficial uses.