Oh, yes... the dreaded constipation! Usually this is from the pain killers (especially morphine), but it can be from the chemo and inactivity as well. We used a natural herbal stool softener available over the counter which was recommended by several of Terry's cancer doctors. If she needs more than a 'normal' dose, that's okay, because the key is making the patient comfortable. At some point we actually used a prescription from the doctor, but it had a tendency to make him sick to his stomach, so we stopped using it. It was like cod liver oil and terribly disgusting for him to swallow.
It is difficult for cancer patients, because the chemo makes you feel like s#$t, but encourage her to eat lots of high fibre foods (bran, nuts, whole wheat bread, lots of fruits and vegetables, popcorn) and more importantly, drink LOTS of fluids! Tea or warm water seems to help a bit, too. Suppositories can be a real help. If she is able, it is important to get lots of exercise. If she tends to sit a lot, but you think she is capable, I would encourage her (go with her) to go for a short walk several times a day. Maybe this is something she'd like to do with your son? If she's up to it, any exercise that's safe for her to do would be great.
Your aunt should discuss this with the doctor because it needs to be dealt with quickly or could lead to her bowels being impacted. It tends to come back, so she should be open and honest with the doctor and ask if she can take more medication if the doses aren't working, etc. The constipation could also be caused by other issues that her doctor might want to explore (high calcium levels, nausea, other tumour growth, etc.).
Sweetie, do you want the truth? The truth is that "USUALLY" (I stress the word), when the cancer spreads from the lungs to the brain, they are not getting better. The chemo WILL take a whack at her, but it doesn't usually cause forgetfulness, loss of memory, etc. The stress can affect her ability to concentrate, just like it does you. Generally, at that stage, the chemo is done supposedly to make the patient more comfortable. With a less advanced lung cancer they usually operate, although not always. I'm sorry if what I say hurts you, but I will not lie to you. I know that you value the honesty... and you know you have lots of support here.
Hang is there. I'm here for you, as are lots of other people here!
Love & hugs, Didi