Problem with my young Bolivian Ram

Hi All,
Hope someone has a clue to what might be going on with him. I've had my tank going for 2 years now and have never had any illness's with any of the fish. Well just one Blue Gourami got ripped fins, in the Q tank with some melafix and he was as good as new.
This little guy lost his coloring, he has dark stripes instead ,also seems a little unsteady when he swims. His fins are a bit ripped in places and yesterday I noticed the other one was chasing him around. Don't know if it's because he's sick or he's sick because he's being stressed by the other Bolivian. I'm going to post a picture, the healthy one is on the left and you can see the dark striping on the little sickly one.I change water once a week, sometimes every other, sorry but summer is an extremely busy time and I'm gone all weekend, but most times and for the rest of the year it's a weekly 50% water change.
Any ideas would be appreciated, I'm at a loss, will try googling fish illnesses too. Do you think I should just get him out of there and put him in the Q tank which now houses 3 ABN's.

Haven't seen the other fish bothering him at all. He's in a 75g with 2 BG's who just chase themselves,9 black phatoms tetras who don't bother anyone, one red hump eartheater who just worries when his next meal is coming and an assortment of bottom dwellers,a whiptail,2 red BN's,4 S. petricola, none of who even looks at him. The params are good, didn't do them today but did them last Sunday night and 0 amm, 6.4 PH, NO2-0 and NO3-10ppm. When I put food in the tank he goes for it and I have seen him eat, however not alot. Other then that I can't figure it out, he just seems to be wasting away.

Jannika I think you've hit it. When I was given the original school of BR's there were 6, they were 2 1/2 yrs old, the tank has been up for 2 years now and I lost several over the last 6 mos. So I bought 2 young ones to keep the last old guy company. Well he just recently passed and now I guess these 2 young ones just have themselves to get tough with. I do have a 10g that's not running, I guess I could get a sponge filter and start it up again. I've watched him and I haven't seen anything coming out of him. I would think if it was some kind of worm more fish in the tank would possibly have them. I was thinking the same way you were and if I'm going to keep them in the same tank I will probably have to add to make it a school again so there isn't one getting picked on totally.

Jannika the last day I posted when I left he was still ok, it was early am and I fed them and left for my dog
club,it's a long day my bf is the training director and we did't finish till 3pm. By the time I got home and went to the tank I didn't see him. Looked all over and couldn't find him. The next day I found him behind a rock. I was really upset, I like the Bolivians very much and they have so much spunk for little guys. When I had the 6 older ones they swam together and occasionally would butt heads and flare at each other, but I never saw them chasing each other to really hurt. There are other fish in the tank and if I decide to get more BR's I'm going to get 5 more and see how that goes. As you know they don't bother other fish and the tank is big enough, so they'll distribute the aggression btwn themselves and not only one on one. I can't believe how upset I was when I found him

Yes they most certainly do, a great little cichlid to have.