i would like to add a few more points to what i have already said about your sons chart, his lagna is free from afflictions and there are benefic aspects of venus and jupiter on lagna so though he will have health troubles it will never be very serious. venus exalted in a kendra is a huge blessing and it will also see that his health is protected, mars strong in an upachaya house also indicates protection to health. so in conclusion i would like to say that lagna lord mercury & the sun getting afflicted & rahu-ketu in the 4-10 axis will give health troubles but the positives in the chart that i have just mentioned above will see to it that it that the health troubles are not serious.
i absolutely agree with you that the worst thing about knowing astrology is getting to know what negative things are there in the charts of near and dear ones and also in one's own chart. like, when my jupiter sub-period started i didn't know astrology that much so thought that it will be a great period as jupiter is in my 11th house of gains. but later on i realized that it also indicates health problems being the 6th lord from the lagna and chandra lagna, that has got me very worried as i am having quite a lot of health troubles in the jupiter sub-period which started 1 yr back and the worst part is it is going to stay for another 1.5 yrs.
"You mentioned in your post about Rahu -Ketu being in the 1-7 axis but Rahu and Ketu are in his 10 & 4th houses. So, I did not understand why you said 1-7 axis."- i mistyped rahu-ketu in the 1-7 axis but i had analyzed the chart taking into consideration rahu-ketu in the 4-10 axis. but still thanks for pointing it out.
i didn't misunderstand you at all and even if your intention was knowing about your son's health, i don't see anything wrong in that, it's very normal, a father's concern for his son's health.
i don't have an answer to your question about whether benefic aspects on the lagna can override the afflictions to the 6th house, it's because i don't know the answer.
let me tell you what i know, the lagna signifies health and so does sun and they getting connected with the 6th,8th or 12th house will cause health problems. malefics associated with lagna, lagna lord or sun will also cause health problems. benefics in the kendras(1,4,7,10) and malefics in upachaya houses(3,6,11) will protect a persons health. malefics in kendras is not good for health.